Please check one by one :
1. Check ur network (nic, lan cable etc)
2. Check the OS with in-built utility tools
3. Check for any suspicious file or object
4. Make sure that ur hardware and OS meet the minimum 2007 Microsoft Office system requirements.
Recommend that u have to perform to overcome ur problem:
i) Defragment the hard disk (for safety, u have to take backup all of ur necessary data)
ii) If possible, optimize the virtual memory use
U may do some tweaking as I providing below :
a) Go to the view tab and uncheck the “Animated Text box”.
b) In Word > in Normal view, check “Wrap to window”.
c) Go to the General tab and uncheck “Provide feedback with animation”.
d) If u work with multiple documents, lift the ‘Recently used file list’ entries to 9 which is highest setting. Or down to 0 if u want to disable the Recently Used File List.
e) If u use simple Auto-Shapes, uncheck “Automatically create drawing canvas when inserting Auto Shapes”.
f) On the Print tab, turn off “Background printing”.
g) Now go to Tools and Auto Correct Options. There is a tab called “AutoFormat As YouType”. Uncheck all the boxes under “Apply as you type” and “Automatically as you type”.
Hope it helps u !