It, er, seems to have fixed itself............ I don't think it could be a virus, because I only installed 2000 last night, and all my email is scanned by the server (either yahoo or, more likely. the uni server). I guess it could be sneaked in through a comms port, but I haven't seen anything symptomatic.... all I can think is that something was 'up' with my keyboard / mouse drivers.
For point of reference, the problem was that i could click and hold down on a file icon to my hearts content, but nothing would actually happen (i.e. no icon). Also, I could cut the file out, but the 'paste' option in the relevant menus would remain greyed out and ineffective.
EDIT: Seems to have gone dud again.... I think it's something to do with my internet connection. Anyone know what scvhost.exe is?