The thing that i really don't understand is that the drive is really not that old, i've only had it for around a year, if that, and it does seem to do it on any computer
It has nothing to do with how old the drive is usually, it could be heat related, some indexing task you have running, continuous defraging, the drive was bad to begin with (if you didn't burn it in and test it) there are so many possibilities
The most important thing currently is to back it up I agree with buwish it sounds like it is circling the drain
Drives are currently cheap just buy something immediately back your iomega up and spend the next 14 day to a month looking for a good deal if you are unhappy with what you bought and exchange it.
Check your warranty and figure out your RMA
Also download the iomega tools and see if it will tell you what is wrong with the drive if not then get the Western Digital tools which I find to be very good and which work with other drives
best of luck saving your data