Do you have other shared workstations at work that could try accessing? see if you get the same thing? There are a few symptoms on why you would get a blank page, but not sure why all of the sudden.. Someone hasn't messed with the internet explorer settings ? If maybe, you could go into Tools - Internet Options - security.. Highlight INTERNET, and click custom level, then click reset. close browser and try again.
But.. actually, don't think you've mentioned.. which browser are you using? And, if you are using one, but have another browser on the system, could you try that browser and see what happens?