Aimsbury's fix worked for me
Thanks Aimsbury - Your fix did the trick for me.
For anyone reading this because they have the 'virus', the way to get rid of it is to do:
1 Open Windows in Safe Mode (turn on your PC and hold F8). If you can't figure this out - Google it
2 When it loads, go to Start and in the "Search" box type msconfig and press enter
3 Choose the Startup Tab at the top of the new window
4 Look down the list for an item with a strange random lettered name (mine was idsifskdse.exe or similar). The command location of it will be in C:\Windows if I remember correctly
5 Untick this and click apply
6 Restart the PC - this time in normal mode. Windows should boot correctly.
7 I chose to restore windows to an earlier point (a week earlier, to be safe). You can Google how to do this if you don't. Search for 'System Restore'
I didn't delete the file like Aimsbury but it's probably a good idea to. Once I did the restore I couldn't find it again though, so hopefully it went. I'd recommend running a virus scan afterwards to be safe.
Thanks again Aimsbury.
FYI, I ended up with this after I tried to watch a dodgy stream of a movie forgetting I had disabled AdBlock Plus on Firefox. Moral of the tale is to go legit and buy the movie!! ...or don't turn ABP off
Hope this helps someone else