wierd...got notified of an update to sleep analyser so tried to update it, only to get told dependency on 4.7.4 issue, which caused it to remove itself, all the python packages and another app - pyRadio which I've had the same issue with. So it was now in a clean state..
Tried re-installing. No joy. Same issue.
Tried again today and works fine.

Two possibilities. Yesterday was using faster app downloader - today just the standard app downloader.
Also - shut down phone overnight and rebooted.

Either way now working fine.

Thanks caco3 for the work!

I'm a windows programmer myself so I don't know anything about linux programming and the dependencies - but from what I've read since this PR1.3 update screwing up several apps it seems possible to have a dependancy on python2.5-qt4-common but without tying it to a specific version.
I don't know how one goes about this, but it would mean that you future proof sleep analyser against any future updates to python2.5-qt4-common.