As mentioned in my previous post, following my GPU upgrade, I experienced some odd behaviour. Strangely enough, the computer worked perfectly directly after the upgrade; I was even able to jump into a game of Skyrim (and be wowed with the massive increase in performance, I might add). However, when I logged into another account, strange artifacts appeared on screen, the screen flickered off and back on and, finally, the whole rig spontaneously rebooted!
Extremely worried there was an issue with the card, I logged back into my account; no artifacts appeared and I was able to run FurMark for an extended period without any problems. However, logging out and back into the secondary account immediately resulted in the same problem. After the machine rebooted again, I tried logging in as the "Admin" account I have configured; same problem. This time I was able to see a message briefly pop up on screen, which I later tracked down in the Event Viewer:
"Display driver stopped responding and has recovered"
Researching online brought up a host of reasons why this message might appear, but considering the issue only occurred in certain user accounts, I was fairly certain that some remnants of the previous card's drivers were causing the issue, and that running the driver installation in my user account had not cleared up other accounts on the system. To test my theory, I booted into safe mode, logged into the "Admin" account and used the msconfig tool to stop the AMD/ATI Catalyst Control Centre from starting when logging in. Sure enough, I was able to reboot and log into the "Admin" account with no problems at all.
After a bit more reading around I discovered a tool named "Driver Sweeper" that some people claimed to have helped them with similar problems. I'm very sceptical about installing any sort of 3rd party utilities on my machine; usually they don't uninstall properly, don't work, or you get more than you bargained for (i.e. ad/mal/spy-ware)! However, given the number of times the tool was referenced on forums, I decided to give it a go.
Once Driver Sweeper was installed, I executed a scan for video drivers and it located several files that I hadn't been aware of and even the installation files that are extracted to C:\ATI! After clearing away all the driver remnants, I rebooted and performed a fresh install of the AMD catalyst drivers in the "Admin" account, before rebooting and testing that I could log into each of the three accounts on the system without issue. This test proved successful, with no re-occurrence of the artifacts or rebooting, and I was safe to use the system normally again!