USB Root Hub problem

[parsifal]

The PC I'm talking about is not mine, and I have to rest on what I remember, so I apologize for any vagueness in advance.

Windows 98 based PC (IBM Aptiva, old AMD K6 -powered) has problems with several (all?) peripheral devices. Latest is a USB printer by EPSON. The Device Manager shows a yellow exclamation mark over the USB Root Hub. I can't remember the detailed info about what the DM informs to be wrong (and I'm not sure about the proper translation as the error message is in Finnish), but as I recall it, USB Root Hub has been disabled because of several failed attempts of... what ever it was. Something about transmission or moving. It was quite a vague term, I'm sure about it, but it was something about transfering something. (I really apologize this...)
It tells me to check the cabling, the devices, and then reboot.

This happens immediately after the printer is turned on. Before this event there's no exclamation mark, and the Root Hub seems to be working fine. After the exclamation mark appears, the device has to be removed in order for it to appear as working again. I've tried both of the USB ports. In BIOS there's not much to configure. Only options about USB are the two of enabling USB and setting it to work in a traditional mode.

And also, with the USB Root Hub the device manager shows a device named ALI PCI to USB or something. Could it be to blame?

EDIT: I forgot to mention, that to some point USB worked fine. Once, however, after plugging in a digital camera (which had worked normally before) just was not shown as a removable mass media storage device as it had been shown before.

This explanation is all I can come up with, so no wonder if it's of no use.

All help is welcome.