In IE, go to Options -> Internet Options -> Privacy -> Pop-up Blocker. If it already is checked off, click Settings and type in PC's URL, click Add, then click Close (or the escape key) twice. In IE 9, Options is represented by a gear cog.

I'm guessing you're using IE 9, although if you don't know which version you're running, go to Options -> About Internet Explorer and you'll get a pop-up window with the information. Unless you absolutely need to be using an older version, I highly suggest upgrading to IE 9. IE in general is known for being a pain in the butt when it comes to web-browsing and web development. Older versions of IE are even worse and it could be the root of your problem.

Hopefully this resolves the problem, otherwise it may be a bit more complicated to figure out the cause. Try to see if you get this same problem with Firefox; if not, then it's IE acting up.