Windows 2008 64-bit, .NET 3.5 Framework still has memory limit
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On a .NET 3.5 Framework, 64-bit Windows 2008 Server system, we are bumping into a 2GB memory limit.  We do not have any single object that is over 2GB (largest object is 700 MB).  The program hits close to 1.5GB, starts becoming unstable, and eventually crashes with the 'System.OutOfMemoryException' error.

We're at a bit of a loss since the 64-bit system should have the 8TB limit and no single object is hitting close to 2GB.  Any thoughts on what could be causing the limitation?  If someone with a Win2008 Server (64-bit) upgrades to .NET 3.5 Framework, are they still limited by the 4GB found in 3.0 (installed with Win2008)?  If so, how do I get around this?