Have you tried reinstalling it in case one or more of its driver files has been corrupted?
If this has only just happened, you could also try restoring an earlier version of the registry. Immediately after powering on, tap the "F8" key until the Boot Menu is displayed. Select the option to boot to "Command Prompt Only" and, at the prompt, type:
and press Enter. You will have a selection of (five) previous registries that you can restore. Select a date prior to the problem and see if that fixes it. It is a straightforward process, just follow the prompts.