What are the causes that MS Outlook 2007 freezes? It's OK a few seconds after launching the application but when I want to do some action (e.g. write new e-mail) it suddenly freezes. Is there some troubleshooting?
I have experienced similar issues.
This was mostly related to either Xobni running or anti-virus. Try disabling anything similar you might have installed and see if the problem re-occurs.
Aside from that, you could always upgrade to 2010, but that might be cost-prohibited.
Recreating your .OST file should fix this issue.
Open Outlook>File>Data File Management>Data Files
Remove file name outlook.ost
The real cause behind Outlook freezing or hanging is the increased size of the Outlook .pst file. To be more specific, the size of .pst file exceeds 2GB or its upper limit. Due to this, any general operations like writing emails, deleting etc get affected and do not work.
To fix the above issue you can try any of the below:
Complete details about these steps can be found here:
Moreover, you could also try some third party PST file splitter software as this splits the PST file in a fast and secure manner.