In many applications and browsers pressing the space bar (when you are not in a text entering situation) results in a scroll down. When your mouse cursor is focused on a text box or when typing in a word processor that default function is disabled. You were able to type this question with spaces does it scroll? If it does, maybe you could try System Restore.
System Restore: frequently asked questions
[http://windows.microsoft.com/en-US/windows-vista/System-Restore-frequently-asked-questions]