Dell desktop, Windows 7 Home, IE 8, AV Sophos
For a couple of weeks I have noticed that most .pdf files fail to open with an error 57 message. Not all pdfs though. Some which were previously on the desktop still open fine, but any pdf attachment in email for example, always fails.
Eventually I thought I should do something about it. I suspected an update to an earlier version of Reader might be to blame so I decided to uninstall it and then reinstall. Used Control Panel to uninstall and it appeared to work correctly (desktop icon removed). When I went on to reinstall I found that the download from Adobe did not work, by which I mean the download Run/Save box showed, then the file permission box asked to allow the file to be loaded, then nothing. Tried again after halting the AV scan without success.
Read a few 'help' files on various boards (including Adobe) and attempted a fix or two. However most solutions required some diagnosic software to be downloaded and as I quickly found no downloads worked!
At this point I used Restore to roll back to a earlier time but within the 60 day period the original pdf problem still exists.
The computer otherwise seems to work normally, although I have noticed it occasionally 'seizes up', for a minute or two before resuming from where it stopped. The AV is up to date and scans regularly. MS updates are installed when available, athough there have not been any for some time.
I have run out of ideas so any assistance would be much appreciated.