a possible solution if ur P9981 touchscreen doesn't work sometime
my P9981 (7.1.0.764 All Lang) used to have a strange problem -- every few days after a phone call (regardless call in/out, not to specific contact), randomly its touchscreen stops working. All keypad & trackpad still works fine, just the touchscreen stopped responding. After battery pull all comes back. I never know when will it stop again, did some tests but can't figure it out. Reload OS, same problem after a day or two.
I downloaded a simple Theme from app world, loaded it up, and the problem is gone. Happy ever after.
My guess: the stock theme for P9981 has some conflict with the 7.1.0.xxx All Lang OS. When I hang up phone calls, the system will load back the home screen, but some embedded scripts may just hang here for unknown reasons. Change to a 3rd party theme (9900/9930/9981 themes), that 'posche customized theme' internal scripts will no longer cause the problem.
After use same trick to solve the same issue on my friend's 9981, I thought I may just put a post here --- good luck if it helps, and please don't ask me why or how if it doesn't work on your phone ...