USB short circuit problem?
Hi, this is my first post. Apologies in advance if this subject has been covered in recent threads, but I'm up against a deadline tighter than a spider's ass. Thanks in advance for any suggestions!
Details: G4 + OS 9.0.1 + fully functional 7 port USB hub. Problem? Plugging the USB hub (connected to a printer, scanner, and modem) into the back of the Mac stops the keyboard and mouse from working! I've tried the old process-of-elimination thing with any number of combinations, all to no avail. I've tried two keyboards, two different mice, two different USB hubs... basically, I'm going nuts. Any ideas?
A million rubies and two of my daughters for the man with a plan!
Details: G4 + OS 9.0.1 + fully functional 7 port USB hub. Problem? Plugging the USB hub (connected to a printer, scanner, and modem) into the back of the Mac stops the keyboard and mouse from working! I've tried the old process-of-elimination thing with any number of combinations, all to no avail. I've tried two keyboards, two different mice, two different USB hubs... basically, I'm going nuts. Any ideas?

A million rubies and two of my daughters for the man with a plan!
Comments
The overloaded/power-drain explanation makes sense - I tried plugging two devices into the back of my Lacie monitor; but my keyboard didn't want to work from there either, nor did any other device (trying to grab the scanner from within Photoshop, for example, only gave me a "scanner not present" message).
Whatever I do, wherever I plug things, I can't get everything to work at once. Totally confused as I can't even seem to be able to isolate the problem to one external device.
Of course, re-installing the OS (or upgrading for that matter) may well solve the problem, but maybe it won't if it's a hardware issue as opposed to a possible driver issue. I swept Tech Tools Pro over the HD, but that came up blank...