After downloading GIMP (to Windows XP SP3), my security software caught a number of mid-level security problems. I uninstalled it (along with some other software I had downloaded and installed the same day) and reinstalled it by itself. I still got the same problems, and now every once in a while the security software will catch problems, when it was not doing so before.
I suspect the download included something that my security software missed. If I edit or create images in GIMP, could they transmit these problems when viewed on a website or elsewhere?
Did you download GIMP from the official website or a website that you trust? I don't think you have to worry about virus spreading through image files, because they are just images and can't execute any code, unless they manage to exploit some nasty bug in some image software but that is probably unlikely.
It may also be false alerted by anti virus software. Until I stopped using freeware ones, I used to receive false reports sometimes. Obviously, it happened very rarely but after checking the files with virustotal.com (which I suggest you, as well) it came out that the anti virus was issuing a false alert.
It i not related to gimp, please look at the messages you get or copy down them here so we can look into them and see what is the problem.
Gimp itself will not give you any alarm even false positive because it is a software that is being used by so many people and even a false positive detection can result many news headers in tech websites which we don't see any now.
So i think the problem is from other software, have you installed anything else after Gimp ? have you seen any dangerous website ? what is your antivirus/internet security ?