Thanks.Two weeks ago I have tried MSCONFIG and disabled the services as you have mentioned and then only posted the problem in the forum. At that time also it didn't work. Now also I tried again and it didn't work. I also did CHKDSK and also tried to install it from downloaded file (903MB). Nothing works. With downloaded method, when I doubleclick the file, after a brief execution (accepting to install SP1), it comes with an error "file not found". There is no help which file is missing and how to recover. About two weeks ago, I didn't have this "file not found" error. It will execute and in the middle (after 10 minutes), it will come up with an error message not installed (with error code; different codes at different times). I also contacted Microsoft help ( in the phone for more than 4 hours) and he accessed my computer remotely. All possibilities, he tried and still the problem is not solved. I don't know what is wrong. The service pack (SP1) and Internet explorer version 9 don't get installed. All other updates from Microsoft get installed by update method. Automatic update also notifies of the update. Now only IE9 is notified and no notification for SP1. Manually I check for updates and SP1 does not come nowadays. SYSTEM files shows no SP1 installed. I don't know what is wrong.
Thanks
Sundaram