Thanks Guys, all taken on board for further attention.

The HijackThis .dll file is MSVBVM60.dll

The computer seems to work fine when first booted, although it is sometimes hard to get to my server in that it will dialtone will sound, but instead of the 'warbling' ring it gives a steady buzzing.

My boy's computer will give no trouble when connected to my phone jack, even though he is using a long phone lead. He did have the same trouble after using one of my Zip disks, but a format of his computer fixed that. Suggestive, eh?

Time seems to be an element of the trouble. If I'm browsing a LONG thread, often I'm not able to post afterwards. It seems to me that the problem is that I'm still in there, but on a VERY slow connection. Last night it took over one hour to download 15mins of windows updates, and the IE update wouldn't download at all.
My chip is a 2.6gig, default clocked. Exactly the same symptoms as my previous 400meg chip. No faster, either.

The Spybot forum FAQ says the file that won't destroy has been fixed by a Windows update, and is no problem anyway.

Now to see if I can post this.