I've helped a few people out over at the Nokia Maemo forum who were seeing this error.. Each time it was found to be a problem with this file:

/home/user/.rtcom-eventlogger/el.db

Here's one example of a thread with the fix.. the downside is it means losing all your conversations/messages.. but I guess if you go into the conversations app its already blank? Maybe you can try and make sure it is blank before you follow this link

http://discussions.europe.nokia.com/...p/635122#M5784

just delete a lot of unnecessary conversations! really! you're probably sitting around 1500 texts by now, where it gives up trying. you can use glogarchive to export them and backup then delete the convo's. just try it before you go flashing or deleting apps or even anything drastic!

In some of the cases I've seen where users were seeing this error, the conversations app showed no conversations at all.. it was already empty.. scrubbing the file causes it to be re-created fresh and things start to work again.. must've seen this about 10 times so far (on other people's N900s)

i've had this message twice now, luckily could still see al my convo's in order to export and delete them, so wouldn't really call it an error in my case, just a notification. but if there are no conversations showing then yeah probably time for more drastic action!

I've got a sample of broken el.db files that the owners had kindly donated.. I'll see if I can't get some sensible debug out using sqlite3 and some poking..

hi, did you resolved your problem yet? my n900 has same problem, thanks for helping

Possible solution:

Possibly related to couple of backup recent restores I found I was getting "device memory full" trying to save or change contact or sharing accounts.

[Unrelated, but this was in the course of trying to resolve some probably inaccurate "application memory full" errors]

I was preparing to reflash and removed the battery to get the device serial number... this mean I had to reset the date and time stuff and ... the 'device memory' issue was resolved.

So... a few seconds with the battery out may help.

... actually, seems I can install apps now too, so it may have helped my "application memory full thing" too.