Probably your block database is getting corrupted for some reason. Maybe due to an antivirus or a bad disk.
The resolution to that would be to try to close the client, remove the blk*.dat files and launch it again (and wait while it downloads the entire blockchain again).
Additionally, there is a newer client than version 0.5.2 now as well. Try using the latest ... v0.5.3
I suppose I did delete blk*.dat when I uninstalled it and deleted whole bitcoin folder
u suggest I do it again ?
I am leaving that one for the end...
I don't know how to create an installation .exe for new version
so I wait until it shows up at weusecoins
It is strange, because it just stopped performing for no reason,
everything else on my pc is working,
so one of my strategies will be waiting for it to repair itself
well, at least nobody is suspicious that this might be some kind of direct attack...