cudaMalloc CUDAStream::Allocate failed GPU memory under Linux

I have an 8800GT. I’m trying to do GPU folding under wine for folding@home. I used to run opensuse 11.1; folding ran fine for months. I recently upgraded to 11.2 and now I get an error “cudaMalloc CUDAStream::Allocate failed” when trying to run folding.

Similarly, if I use the memtestG80 application at default size (128 MiB) it returns an error – not enough GPU memory free.

I can’t understand why my 512 MB card doesn’t have any free memory. I have no games running.

Sometimes folding works for a few hours on first reboot of the system, then fails.

Can anybody tell me the problem/solution?

Details:

Point of View 8800GT 512 MB, Linux 190.53 drivers [NVIDIA-Linux-x86_64-190.53-pkg2.run], 32 bit CUDA toolkit [cudatoolkit_2.3_linux_32_suse11.1.run], not overclocked.

opensuse 11.2 64-bit, KDE 4.3.1 Kwin enabled
Monitor: LG W2361V 1080p via DVI
PC: 3GB RAM, Athlon X2 4600