photoshop brush issues... please help?

okay, i'm finally going to just break down and ask because i can't seem to figure out the problem on my own (and it's been almost a week now and i'm frustrated). i've had photoshp 7 for a good long while now and there has never been an issue. well, a couple days ago when i went to load new brushes (as i've done many times) .... i click on the little circle with the arrow and the drop menu never shows up.

i cannot get the drop menu for brushes to come up when i click the circle. it as never ever done this before. at first i thought i just needed to restart my computer but that hasn't helped. i even cleared off half of my entire c drive because i thought it was an issue of GB space. nothing. i started being crazy and deleting brushes but after deleting some didn't fix the issue, i stopped - as it stands, i already deleted some of my favourites and cannot reload them due to this issue.

any advice would help, though i have to confess i'd rather not have to reinstall the entire program. i keep thinking there has to be some way to work around it... so here i am, hoping someone might have an idea. thank you all so much in advance!