Seems that quite a few people are experiencing problems with Super antispyware. I had the same problems as you did, except that instead of no hdd, my ext drives would not show and 50% of shortcuts on the desktop had gone. Then during a scan the pc froze and required a re-boot, on re-boot all my settings had changed, nor could I connect to the internet and my encryption program would not open and my half the programs and data files appeared to be missing from all my drives!It took 3 attempts to do a system restore but that solved nothing nor could I re-establish an internet connection. It took a destructive re-format and re-install of windows to get back online. Fortunately most of the data I had lost had been backed up to dvd's and I had all programs ready for re-install with the exception of the encryption program.
Once back online I was able regain my encryption from an online source and open my encrypted volumes though they too had been decimated! Again I could recoup most of the data from online sources but will take me some time.
My suspicions say either it was a virus that was not picked up by AVG or that Super Antispy was at fault, leanings are towards the latter and have not re-installed that prog and have had no problems since. I know that many are running the program without these problems but it does seem that it is causing others big headaches!