Article ID: 253912 - View products that this article applies to.
This article was previously published under Q253912
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If a computer that is running any of the versions of Windows that are listed above contains more than 512 megabytes (for example, 768 megabytes) of physical memory (RAM), you may experience one or more of the following symptoms:
The Windows 32-bit protected-mode cache driver (Vcache) determines the maximum cache size based on the amount of RAM that is present when Windows starts. Vcache then reserves enough memory addresses to permit it to access a cache of the maximum size so that it can increase the cache to that size if needed. These addresses are allocated in a range of virtual addresses from 0xC0000000 through 0xFFFFFFFF (3 to 4 gigabytes) known as the system arena.
On computers with large amounts of RAM, the maximum cache size can be large enough that Vcache consumes all of the addresses in the system arena, leaving no virtual memory addresses available for other functions such as opening an MS-DOS prompt (creating a new virtual machine).
To work around this problem, use one of the following methods:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
Vcache is limited internally to a maximum cache size of 800 MB.
This problem may occur more readily with Advanced Graphics Port (AGP) video adapters because the AGP aperture is also mapped to addresses in the system arena. For example, if Vcache is using a maximum cache size of 800 MB and an AGP video adapter has a 128-MB aperture mapped, there is very little address space remaining for the other system code and data that must occupy this range of virtual addresses.