Original Title: LSASS using majority of CPU.About once a day, my computer slows down to a crawl and becomes useless. According to Windows Task Manager, the culprit is LSASS.exe. It uses up almost all my CPU and this can last up to 10 minutes. Why does this happen and how can I make it stop? Thanks.

Hi,This problem occurs if the virtual memory address space of the Lsass.exe process is fragmented.You may follow these steps & check if the issue persists.Before we proceed, please first backup the Registry.Important: This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry in Windows:http://support.microsoft.com/kb/322756a. Click Start, click Run, type ‘regedit’ in the Open box, and then click OK.b. Locate and then click the following registry subkey:HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsac. On the Edit menu, point to New, and then click DWORD Value.d. Type UseLowFragHeap, and then press ENTER.e. On the Edit menu, click Modify.f. In the Value data box, type 1, and then click OK. On the Registry menu, click Exit to quit Registry Editor.Hope the information helps. Please post back and let us know.RegardsDebleena SMicrosoft Answers Support EngineerVisit our Microsoft Answers Feedback Forum and let us know what you think.