If you are using Internet Explorer, I would suggest you to follow these steps and check if it works:
a. Open Internet Explorer.
b. Click the Tools button or press Alt key + X, and then click Internet Options.
c. Click the Advanced tab, and then browse to the Accelerated graphics section.
d. Click to select the Use software rendering instead of GPU rendering check box.
e. Click Apply, and then click OK.
f. Close all open Internet Explorer window and then test the issue.
I did that and it still won't work.
I guess I can add this to the list of problems I have been having with Windows 8 (Flash not working, updates stopping at 13%).