I started this question over in the Windows Client TechCenter, but was referred here after a few exchanges of posts. This is a summary of the problem so far.

I've a intermittent problem with W7 Pro 64 bit. It mostly effects Outlook 2007, but other non-MS programs suffer as well.

Outlook is slow to start up -

1. Click on Outlook shortcut on desktop and the chose profile box comes up instantly,
2. Select the profile and the main Outlook window remains completely blank for 30 or more seconds
3. Then the LH column appears, but it is also blank.
4. Finally the LH column populates with mail folders and the main viewing area also shows up populated with emails (new and old)

One or two other programs show similar slow starts, whilst most are very fast due to an SSD for the C drive, including the other parts of Office, Word and Excel and the Adobe suite.

The Outlook startup problem persisted for about a week, then went away and now it's back even worse.

Associated with this is repeated loss of cursor and keyboard entry focus. Whilst I have been typing this the keyboard input has frequently ceased to appear on the screen, cutting off words in the middle. I have had to go back and retype stuff every few words. For example I will now type quick brown fox without corrections:-

The qbrown fox jumps over the lazy dog

Notice how it lost most of "quick" in this case then regained the focus for the rest of the sentence.
The loss of focus also applies to the mouse cursor - it freezes briefly then jumps.
Automatic Windows update is enabled and the latest drivers installed. (it's an MS wireless Mouse)
I've checked that Office 2007 SP2 is already installed.
Today I've installed two optional Windows 7 updates:-

Microsoft - Other hardware - Microsoft Hardware USB Mouse
and
Update for Windows 7 for x64-based Systems (KB2488113)

I've just installed W7 64 bit SP1 (KB976932)
All to no avail.
The stuttering keyboard input and jumpy mouse are associated with Outlook. If it is running then it triggers the anomalous activity about every 10 seconds. If it isn't (like now, I've shut it down) I can enter text with no problem. The problem persists even when typing emails in Outlook itself.

Further investigation shows that the OST file is huge - 5.6Gb! My understanding is that it is used for off-line working with Exchange Server. I never work off-line and I don't have Exchange Server, so do I need this file at all? Reading posts and advice in other sites seems to suggest that it can be deleted and Outlook will rebuild it if necessary. Is this correct? Dare I try it?



Later - I managed to run compact on the ost file, but it's only reduced it to 4.9Gb and Outlook still loads slowly and the input problem isn't fixed.