Now I have tried the new installer, but it still doesn't work.
Here's the log from the first run after installation:

args passed:
'D:\Foldit\Foldit.exe'
'-dynamic'
Can't open options file options.txt. (..\..\..\mini\src\interactive\application\Application.cc:77)

Here's the list of files:
23.08.2011 18:53 221.696 Foldit.exe
23.08.2011 18:53 82.214 icon.ico
24.08.2011 06:11 0 inital_run
24.08.2011 06:11 152 log.txt
24.08.2011 06:11 0 stderr.txt
24.08.2011 06:11 0 stdout.txt
24.08.2011 06:11 48.904 uninstall.exe
23.08.2011 18:53 32 version-binary.txt
23.08.2011 18:53 32 version-database.txt
23.08.2011 18:53 32 version-resources.txt

Try "run as administrator". Looks like program can`t access to options file.

Running as admin doesn't help.
I tried copying a working options.txt from a different computer.
No luck:

args passed:
'D:\Foldit\Foldit.exe'
'-dynamic'

I notice this:

args passed:
'D:\Foldit\Foldit.exe'
'-dynamic'

and

args passed:
'C:\Program Files (x86)\foldit\foldit.exe'
'-dynamic'

The last one seems correct for a win 7 64-bit install.
Have you checked the c:\program data\ directory tree for the data files ?

All the files seem to be there:
1442 Files
97 Directories
131856109 Bytes
Since Foldit can write the log.txt and the initial_run files it's probably not an access rights problem.
Foldit is freezing before it can write a fresh options.txt

Load new win installer and install it in another location.
Then copy all.macro file to get cookbook in place and try running it.

No, copying all.macro has no effect.

Tried using new installer (from 2 days ago) and installing it in another place?

yes, as you can see in my comment three days ago

Really odd. I too have win7 64 and no problems at all...

I have uninstalled some random programs now.
For example "Host OpenAL (ADI)", which is part of the sound driver (I think).
Foldit now seem to work properly.
That's really wierd.

I am also experiencing this issue on two separate systems. One system is running Windows 7 and one is running windows XP.

I installed Fold.it only 5 days ago and it worked correctly. Now, attempting to start Fold.It results in an empty window. My privileges have not changed nor have my drivers. I tried uninstalling and reinstalling with the latest installer without any success.

I have attached log.txt from the windows XP machine for your review.

Could you upload a copy of our DxDiag output?

To do this:

* Start -> Run -> dxdiag
* If there is a button that says "Run 64-bit DxDiag" press that
* Check the box that says "Check for WHQL digital signatures"
* Click the "Save All Information" button
* Save the file somewhere and then upload it here

Note: This file will contain your system details, including your machine name, driver details, and hardware details. Feel free to remove any of the information you do not want to be public.

On the XP machine I WAS able to run the application without a problem later in the same day. I did not update the installer or drivers.

I have attached the successful log.txt and slightly modified DxDiag.txt as your requested.

Sorry, the log.txt file did not stick for some reason.