Hey, I had a similar problem with my 24HD in Photoshop. Windows 7 also. Everything worked fine for a while, but every 10th stroke or so was full pressure, no matter how light I pressed it. I could fix it with changing the "Tip Double Click Distance" in the Wacom Tablet Properties to "Off". Hope this helps.
We've been having some issues with pressure sensitivity with our 22HDs recently too. Only the concept artists in Photoshop though. All the pressure levels turn into 100 percent suddenly. We've tried swapping cintiqs, pens, etc, but no luck. It's possible it's an issue with the recent drivers. Try and make sure your cables…