outlook 2003 freezes when deleting contacts

Wonder if anyone can shed any light...
am using OUTLOOK 2003, VER 11.0 BUILD 5608.5606
on xppro, 5.1 2600 sp2 build 2600

I have been trying to tidy up my contacts list/address book but after deleting an entry, sometimes just one, sometimes no more than a few records, OUTLOOK freezes and I get msg says this program not responding ....and usually i end up closing outlook via task manager.....

Since i need to get rid of quite a few contacts this is posing a problem....

Appreciatete any help / suggestions etc...

cheers
andrew