Strange Error

I’ve been running the same code for about 2 months on the same imp.
This last week I added imp.setpowersave as the device was chewing batteries like mad.
Connected to the imp is a PIR, it triggered this morning but I got the error below. It needed a hard re-boot to get going. Working fine now, anyone seen this or explain this?

Saturday, January 05, 2013 07:25:07: ERROR: trying to set 'null’
Saturday, January 05, 2013 07:25:07: ERROR: at swEvent:60


Would be useful to see what was at line 60? It’s possible that the release-14 update upset your code in some way, but I’d need to see the code to comment.

Hugo have all imps got release-14 as this one was running 11.
Will PM mac & code.