Windows 7 Cursor Problems in Windows 7 RTM

I am using Windows 7 RTM downloaded from Microsoft Technet site on 6 August. I having problems with the cursor jumping around while typing text in a text box especially in Yahoo Messenger. While typing the cursor would jump back to a prievous point in the line of text or sometimes highlighting the previous text and delete it when you type the next letter. At first I thought I thought with was a problem with Yahoo Messenger but I notice it did it with one of my broswers. I did not notice this problem with Windows 7 RC at all. Anybody else using RTM and Yahoo experiencing the same problem? Any help would be appreciated.