I read your previous post, but didn't answer because I didn't really know what to say. I'm glad it's all worked out, though.
Ash should take Theland's advice and keep a log of future 'incidents' - just in case. IT technicians aren't above corruption, in my experience. I have all sorts of 'illiegal' software on my work machine (ie. stuff that 'they' haven't installed - media players, web browsers and so on, nothing 'bad' as such) that IT see every time they come in, but they never say a word.
It may be worth asking your question in Technology, re. IP addresses. There's also a way of getting something called an 'event log' from a PC, which a friend sometimes used to do whenever he called IT to his machine. I don't don't know how relevant that is, though. Again, maybe the technology bods could answer your question.