Malwarebytes: take a bow!
Since I started this thread with my suspicions with AVG, the problem has continued to bother me. I had run my antispyware suite, Malwarebytes,Superantispyware and Spyware Terminator without result previously but yesterday, I removed AVG and installed Avast. I took the option of doing a full bootup scan before XP started, but this also brought up nothing as did a repeat scan when Avast had settled in and updated itself. I noted also that Spyware Terminator considered itself up to date but there appeared to be a problem with the updates for Malwarebytes and Superantispyware. The latter stated that updates were available, but on clicking on the update facility, a screen stating "updating" appeared and indications that a download was taking place were seen, but these continued for an hour without any further developments! Malwarebytes could not access its update server and accused me of changing my firewall settings. The problem persisted even when I disabled my windows firewall. After much messing around, I decided to delete Malwarebytes and upload the latest version which I hoped would be more up to date than the one I had already been using. This proved not to be a problem, but it reported an error as it installed itself. This did not fortunately stop it running, so I used this new version to perform a scan. Within munutes it had found about 5 trojans in the win32 section of XP. Some were deleted and others moved to the virus vault when I used the automatic facility for curing the infection. Then a restart was required. I did this with a little trepidation anticipating the probable use of my bootup disk to repair windows, but no - everything started up correctly. On checking, immediately after this, Avast immediately declared that it had updated itself, Spyware terminator declared itself in need of updates which it promptly downloaded. Superantispyware again reminded me that it needed updates and on clicking on the update facility this time, said updates were promptly downloaded and the software was updated in minutes. Finally, Malwarebytes no longer had problems with my "firewall" and was able to obtain its own updates as well. If I re-load AVG, I expect that this will probably update as well!
Where had these trojans come from? Obviously they were new as AVG did not spot them in the first place and they were sufficiently sophisticated to stop it, and much of my other antispyware arsenel from updating itself to ensure that they were never detected. These viruses seemed to have done little else to my machine. I have had no unexpected popups or any other form of unwelcome advertising. There is no evidence that my address book has been transmitted elsewhere or that a keylogger has sent my confidential information to any unauthorised location - but I haven't checked my bank account today yet!
P.P.