Can't attach files to Outlook or Gmail

About two months ago, all of a sudden, I couldn't attach any files to emails, whether in Outlook or GMail, the two services I use regularly for attachments. What happens is this: I click the attachment icon and Finder opens, though slowly, and then I click the file I want to attach, and that's it...the spinning wheel comes up and never ends. I go to Force Quit and see that either Outlook or Safari is "not responding". I'm tempted to think it's a Mavericks problem because this issue happens in both Outlookk and GMail. I couldn't find anyone else with the same issue on line, though there are lots of threads about attachment problems. I can drag and drop files in both programs, but I'd prefer the simpler way. Any suggestions of what to do?

My computer is a 2007 Intel-based iMac running Mavericks. 4gb ram. Outlook, OS, everything updated as far as I know.