Do you have a CD with the driver you can re-install back onto your computer. If you don't you can probably find it on the Iomega website - http://www.iomega.com/global/index.jsp .
Another thing that you mention, is that you are running Norton System Works and AVG. Running more than one antivirus program can cause conflicts and will counteract one another. Also, antivirus programs tend to hog resources...another reason to stay away from using more than one.
I strayed a bit from the original question, but I hope that helps.
Thanks for the reply. The TPP300.sys driver is indeed an Iomega driver that installs from the HDD installation disk, which I do have. That is how first I attemped to reinstall the driver because Windows was not recognizing the E: drive (portable hard drive). Evidently there are problems with this issue because Iomega have suggested fixes on their website i.e. download new drivers etc. all of which I have tried. However if one runs a "find" program for the newly downloaded driver or the original disk for some reason Windows cannot find it - even drilling down several layers. I have had several live chats (over the past 7 days) with their help tech's who have no idea how to deal with the problem I described above except to say it is a Windows problem.
I ran a Google on TPP300.sys and came up with many hits. From this I downloaded a freeware program from RATOC that contains this driver among others. When I do a "find" search it is now present on my C drive. I copied the driver folder to my desktop. I have tried to install it from "Add/Remove New Hardware" as well as from Device Manager. Device Manager does show "portable hard drive under the USB hierarchy but when I open it the driver is not installed. When I try to install the driver it first does a search and then points to the C:\Windows\inf file as the location of the driver. The next window tells you to click on it to install the driver from that file but it fails to find it even though it is definitely in that folder as well. So I change the hierarchy to point at my desktop and the folder but Windows comes back still pointing to the INF file. There must be some glitch in what I am doing.
Also, I did not reinstall Norton antivirus for the reason you quote above. Does anybody have further thoughts? Thanks.