Sounds like you found it the easy way, but be aware there are three broad areas that fill up "silently".C:/windows/tempC:/documents and settings/[user name]/local settings/tempThe third is is your Internet cache, which is easier to clear by selecting Tools, Options, "Delete..." offline cache/temporary Internet files, something like that.That last one was most likely, considering all these pictures are on flickr and being uploaded.
These folder would all be caught by CCleaner.Also, it might be a good idea to go into Internet Options and limit the IE Cache size to something more logical - like 25-50MiB instead of the default (which I think is a % of total disk space or some such, which makes it insanely big)