As requested by crunchie I am posting this as a new thread.
Have an XP computer that is continually displaying
C:\windows\system32\append.dll is not a valid Windows image.
Crunchie has suggested I run SDFix.exe and also Highjackthis.
I have run Spybot on this computer and also doing full virus scan right now which will take some hours to run.
In the meantime as I have never used highjackthis - can you please advise the steps I need to go through with SDFix and HighJackTHis please ?