help with the plus sign

A while ago some changes were made that caused some troubles with some of the links already in my blog. That is, the topics that contained two words, originally were linked with a plus (+) sign between the two words. Now, that doesn't seem to work. I've worked around that...but...today I tried to delete a file from a blog (one of my student's blogs) and I find that this is causing the same trouble....I'm getting this message....

URL /cindyreid/files/klm+test/delete was not found on this server!