PE will not start

Sometimes I try to start PE and I can hear the hard drive responding, but nothing else happens. Other times I get a startup window, plus, in another window,the message that I've copied below. Then, after I hit ok, there's a message about no valid license behind it. Any suggestions? More of the error message below. I checked and the file is indeed in that directory. "This application has encountered an error: 0x0, with the following description: The operation completed successfully. Additonal information: Unable to load the main module: C:\Program Files ...blah blah blah 0xC000007B blah blah blah" Other recent, possibly unrelated problems that might be clues: the little Google window on upper right of Firefox crashes. Spambot in other CoCreate group says I'm not using the right format when I type in the words. I think this started around the same time I started seeing a weird little window about plug ins. A window that wasn't very clear about what I was supposed to do. I sorta guess this might be some kind of Microsoft issue, but I don't know. Thanks!