Please upgrade your driver to the latest available driver. If you don't upgrade the server will not be able to send you workunits anymore as old driver are not compatible with the cuda3.1 application.

gdf

Just to be clear, CUDA3.1 requires drivers 256.xx or newer correct?

Also how will this affect older cards?

The fermi's should also become more efficient iirc?

FAQ - Minimum GPU Driver Requirements

For the cuda 3.1 based apps the minimum driver requirements are,
257.21 for Windows
256.40 for Linux

Note that some more recent GPU's require a more recent driver just to work.
For example, the GTX590 requires at least 267.91 (Win) and the first WHQL is 270.61.

FAQ - Recommended GPUs for GPUGrid crunching

Note on the GT240. This card presently works well on most setups, but not so well with the 6.13app. As the 6.12app will be phased out when CUDA 4000 is introduced (probably some time between May and July), it has been moved off the recommended list. Ditto for other CC1.2 cards such as the GT340.

I would add that they will still work, but should only be used with the shorter tasks. Although they can complete long tasks within 5 days (about 3 or 4) this is not really beneficial to the project, as tasks get resent after 2 days.