The M&M ComDev has posted a note on the official forum about patch 2.0, possibly arriving in April:

"Back in July 2012, when the revamped townscreens were introduced, the dev team used a specific rendering method to support pixel-precise selection of the buildings. This method at the time worked just fine with the current Nvidia drivers’ version. No related crash was detected, neither by our tests or the community, since the method was supported. In October 2012 Nvidia released a new version of drivers that changed the support of a few methods for some Nvidia devices, leading to the so-called Town Screen crash. This affected several other games across the board, not only Heroes VI. The issue was difficult to pin-point as it had a quite unpredictable reproduction step and unreliable reproduction rate. For many months the M&M team has investigated hand in hand with Nvidia teams, until we came to a breakthrough two weeks ago. We have now fixed our rendering method and so far the fix seems to be rock solid. We still have some tests to run on our end and we hope to be able to release the 2.0 patch beg of April."

Meanwhile, before the patch is released, the only solution to the problem will be to roll back to Nvidia drivers 301.42.