I'm running into the same problem. If I edit a DNG in Photoshop it will show. But if I try and edit a JPG or TIF in Photoshop I get the gray screen and the photo will only appear if I drag the window. As soon as I set it down it goes back to gray screen.
I've done the preferences reset and I've tried with and without the OpenGL Drawing option in the performance preferences.
Here's the system info it will help troubleshoot this problem:
Adobe Photoshop Version: 12.1 (12.1x20110328 [20110328.r.145 2011/03/28:10:30:00 cutoff; r branch]) x64
Operating System: Windows 7 64-bit
Version: 6.1 Service Pack 1
System architecture: Intel CPU Family:6, Model:5, Stepping:5 with MMX, SSE Integer, SSE FP, SSE2, SSE3, SSE4.1, SSE4.2
Physical processor count: 4
Processor speed: 2660 MHz
Built-in memory: 3884 MB
Free memory: 634 MB
Memory available to Photoshop: 3251 MB
Memory used by Photoshop: 70 %
Image tile size: 128K
Image cache levels: 4
OpenGL Drawing: Enabled.
OpenGL Drawing Mode: Normal
OpenGL Allow Normal Mode: True.
OpenGL Allow Advanced Mode: False.
OpenGL Crash File: Not Detected.
OpenGL Allow Old GPUs: Not Detected.
Video Card Vendor: NVIDIA Corporation
Video Card Renderer: GeForce 310M/PCI/SSE2
Display: 2
Display Bounds:= top: 0, left: 1366, bottom: 1080, right: 3286
Display: 1
Display Bounds:= top: 0, left: 0, bottom: 768, right: 1366
Video Card Number: 1
Video Card: Intel(R) HD Graphics
Driver Version: 8.15.10.2202
Driver Date: 20100825000000.000000-000
Video Card Driver: igdumd64.dll,igd10umd64.dll,igdumdx32,igd10umd32
Video Mode: 1920 x 1080 x 4294967296 colors
Video Card Caption: Intel(R) HD Graphics
Video Card Memory: 1718 MB
Video Card Number: 1
Video Card: Intel(R) HD Graphics
Driver Version: 8.15.10.2202
Driver Date: 20100825000000.000000-000
Video Card Driver: igdumd64.dll,igd10umd64.dll,igdumdx32,igd10umd32
Video Mode: 1920 x 1080 x 4294967296 colors
Video Card Caption: Intel(R) HD Graphics
Video Card Memory: 1718 MB
Serial number: 91198533994816854015
Application folder: C:\Program Files\Adobe\Adobe Photoshop CS5.1 (64 Bit)\
Temporary file path: C:\Users\paap\AppData\Local\Temp\
Photoshop scratch has async I/O enabled
Scratch volume(s):
C:\, 116.4G, 37.3G free
Primary Plug-ins folder: C:\Program Files\Adobe\Adobe Photoshop CS5.1 (64 Bit)\Plug-ins\
Additional Plug-ins folder: not set
