windows XP SP2 -- won't boot

Hi all. A quick forum search didn't turn up any previous threads with obviously same problem as mine so here goes:
I'm running a Gateway that's about 5 years old, Pentium II ~450mhz, 1Gb RAM, Windows XP SP2. Recently the power supply died and I had to resort to a replacement part that was not exactly identical to the failed part as this part is no longer available anywhere. About a month later now my computer has started acting funny. Pushing the power button does gets power to machine but it doesn't always boot. Usually boots after 2-3 attempts. (Have to power down by holding in power button in between attempts.) Seems to be getting worse. Most times the Gateway BIOS screen appears and then goes black. Occasionally brings up blinking white cursor on black screen after that and then goes black. Rarely brings up cursor then Windows boot screen then goes black. And then finally, sometimes it goes through all those and then brings up the blue Windows screen and I know it's going to work.

Recent scans by Spybot and Sophos AV did not return any malware. Suggestions? Is this hardware or software related? Thanks.

The old power supply was 160W, new one 180W, so I don't think it's underpowering. Dust could be an issue, will try to clean it out this afternoon. Anybody have other tips for troubleshooting this? thx.

Llogg, you should try booting the system from a CD running a couple of diagnostics. I'd start with a memory test like the MS Windows Memory Diagnostic, or [URL="http://www.memtest86.com/"]memtest86. I'd also run the hard drive diagnostic from your drive's manufacturer (most likely Western Digital in your case, I'd think). If you can't get the machine to boot consistently from a CD, I'd suspect a bad motherboard, but I'd try the RAM and HD tests and let us know the results.

Hard drive diagnostic found bad sectors that may be repairable but this may cause data loss. If I need to back up my whole hard drive I'm in trouble. I don't have that kind of storage. I'll run the memory test when I have more time. Thanks for your help.

One more thing. I noticed on trying to boot this morning that at the BIOS screen I get the message CMOS Cheksum Bad. Could this be the cause of the problem? Thanks again.

Cmos checksum bad means that the battery that keeps alive the bios settings when the machine is off has run out. Usually it does not mean that it will affect the machine - however, it may cause the bios not to detect the drive - that coupled with the drive errors means you are even less likely to get it to boot.

I suggest you get an external hard drive, coax it into booting just once more (don't use it till you get the hard drive) then get the machine up, plug in the usb drive (make sure it has a separate power supply!!) and copy the stuff across as soon as possible.

Because you have disk errors, you may not get a clean copy - that is, the files are already corrupt... not alot you can do about that.

Make a back up copy always - and remember a back up copy is the 2nd copy of the data, not the only copy!

Thanks NooNoo. I'm waiting on the external hard-drive. How do I fix the problem with the battery? Thx.

That entirely depends on the laptop and how good you are at taking them apart! Exact Make and model please? (general spec is not a model!)

Llogg, it isn't likely you could clone the hard drive successfully at this point, but you have a decent chance of copying your data files. More importantly, the diagnostic results mean you should probably budget for a replacement drive for the laptop, since the current drive appears to be failing.

I appreciate all the help so far. I'm just waiting on the external HD I bought yesterday to be delivered so I can back up as much as possible. I don't need to clone the HD, but there are a lot of data files that I'd hate to lose.

@NooNoo: This is actually my desktop. It's a Gateway E-4100 with Intel 865G chipset.

:confused: OK, I'm not sure where the desktop/laptop confusion originated, but that makes things easier for you, llogg. The CMOS battery is a quarter-sized chrome disk in a holder on the motherboard. It should be obvious, and easy to remove and replace. It's almost certainly a Sony CR-2032, but any equivalent Duracell or whatever will work fine.

A desktop also means that your replacement drive will be cheaper, faster, and have higher capacity than the equivalent laptop. Good luck on the file copy!

So I successfully backed up the ~70GB data I didn't want to lose, then ran the repair utility on my HD, then replaced the CMOS battery and it booted up first try! I haven't put it through multiple cycles yet b/c I have some work I want to do today and if it's not going to boot up I'd rather find out later. I guess the next step, if the problem recurs is new HD. If I find a good deal I might just upgrade anyway. Thanks for all the help and I'll update after a few boot cycles have been done.

Anytime, but remember a backup copy is a 2nd copy, not the only copy!! Burn off files to cd or dvd to create a library of older files that you don't need on a day to day basis.

Well, okay. Decidedly not fixed. Took seven attempts to boot this morning. I'm afraid a new HD won't fix the problem either, and it seems I can find a new machine for nearly the same cost as a new HD (albeit a larger HD than I've got now). Rather than spend 75% to find out if a new HD will fix the problem I might just get a new computer entirely. Certainly is disappointing.

How much is the new hard drive you are looking at? Or do you mean you can get a second hand computer rather than a new one?

A brand new 80GB hard drive is $40 USD at NewEgg.com!

Or do you mean a new hard drive fitted and all the data transferred by a technician? And if so, how much did s/he quote?