[Freesurfer] VGL error

Hello FreeSurferers,

I run tksurfer remotely from a linux machine running CentOS (Boston University) using Virtual GL/TurboVNC. I have been able to do this successfully for years but have recently encountered the following error when calling tksurfer:

surfer: tkoInitWindow(RMAUT015) [VGL] ERROR: OpenGL error 0x0502 [VGL} ERROR: in readpixels - - [VGL] 624: Could not Read Pixels

The error occurs after the tksurfer image window is started but before a brain surface is displayed. I have confirmed that the error does not depend upon what ssh tunneling tool I am using nor on what time of machine I am using locally. Does anyone have experience with this problem? Suggested solutions?

Cheers, Jason