Ive been doing a little stuff with the Twitterize library and the twitter API.
I started unexpectedly getting a 401 unauthorized error when things had been working fine previously.
Eventually I tracked this down to be an issue with clock sync. I am using VM Ware fusion on Mac and when if suspended then resumed my VM the clock wasnt always in sync. When this was fixed it all works fine.
Note to self the way to change the VM is
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1021718