You should update drivers to the latest drivers.
This will let you receive the cuda23 application which should solve your problems.

gdf

You should get your video card drivers directly from NVidia rather than using a Microsoft update service!

http://www.nvidia.co.uk/Download/index.aspx?lang=en-uk
Or similar, for different regions.

Your GTX9800+ card uses a G92 core, and there is a CUDA bug that causes issues with G92 cores and CUDA 2.3.
As you are using driver version 19107 this bug will be exposed more than with more recent drivers. If you do decide to try to run that card, you should update the driver and select Boinc Preferences so that the card does not crunch GPUGrid tasks when you are using the computer:
I fould that Crunching and playing videos dont go together on the G92 cores. This might also include surfing; with all the online media content these days.

Your GT130 cards uses a 65nm GPU core (G96M). Relative to other cards of this level, it will be more prone to heat & cooling problems. It may also struggle to complete tasks in time; it only has 32 shaders. Even if the system was on 24/7 some tasks would take 3days to complete. It is asking a lot of any program to run for 3 days without any glitch, so to run one set of calculations for that time is always likely to be error prone.
That said, most problems are being caused by a CUDA bug. When GPUGrid moved to CUDA 2.3 this new bug seemed to raise its head, and was at first difficult to identify. It seems to primarily effect G92 cores, but is known to cause problems with the GT200 (Not GT200b) and obviously the G96m cores to some extent too.
After checking dozens of tasks from many people, the TONI_HERG tasks tend to fail more than others, but this is not to say that other tasks will not also fail.
I would suggest that you keep an eye on the tasks arriving at your system and abort any TONI_HERG tasks that come in. It would also be a good idea to make sure you do not receive more than one task at a time. By the time you finish one task the others deadline will be rapidly approaching!
I see from your message that you have already implemented the other good suggestions (dont run tasks when system is in use). I managed to improve my GTS250 performance from 25% lost time to about 11.5% lost time. It is still improving. The techs also looked at reducing some task lengths, and were at least asked to look into an allocation system based on the cards people have.
One last thing to watch out for is updates, these tend to force applications to close and restart your system. Forcing applications to close crashes tasks!

So a bit of PC management might improve things.
Good luck,

Leaving the application in memory while suspended is a good idea. If you close Boinc and then open it again, tasks resume from their last saved positions. This could be 1 second ago or more likely, several minutes ago. So if someone kept stopping and starting, and did not keep tasks in memory, they might not get through any tasks before the deadline.