I'm reporting this problem for a co-worker who has just started using IDEA 7. I haven't seen this problem yet myself. When he goes to Version Control -> Update Project, it immediately pops up a window saying "All files are up to date" - it doesn't seem to do any scanning. But he knows this isn't true and when he goes to a file that he knows has been changed in the repository and uses CVS -> Update File, it does update the file and pull down changes from the repository. The file's CVS -> Show History also indicates that before he updated the file, the working copy was at a revision just before the latest revision in the repository.
He has tried deleting his IDEA system caches and restarting IDEA. It still does the same thing after rebuilding the caches. He turned on the logging of the cvs client/server output to the cvs.output file but it doesn't seem to be created.
If he uses CVS -> Update Directory on the root directory of his project, it updates the files as expected.