Your problem is that your using an eMac. Buy a real computer. I'm using a brand spanking new G4 with RAID 0 on two maxtor 133Mhz diamondmax9's and two kick-butt monitors over a high-speed DSL line. I don't have that problem!
There are a few possible problems...
1.) Your not using the current version of Uplink. Check for an update.
2.) Your not using the current version of OSX and OpenGL. Check for an update.
3.) Your player file is somehow corrupted. Try restarting.
4.) You are using conflicting apps or "extension". Make sure that you haven't installed to many of these retarded apps where things dance on your screen and other such nonsense. If your really desperate, try reinstalling your system software (Be prepared for a lot of downloading, and for the love of gott, BACK UP EVERYTHING.) I do this once every 6 months or so, but I have a lot of hard drives I don't use.
If none of this seems to work, you might want to write a bug report to ambrosia. Inform them of the lengths you have gone to in your attempt to rule out other factors. If they make a suggestion on how to fix it, try it, and immediatly reply so that they know there is a viable problem. Take into account though that Uplink is a horribly buggy game, in gameplay, interface, and graphics. It is very fun, but I consider it to be only a beginning to what will be an undoubtedly good sequel.
Jenova Mantooth