Problem:
The windows system seems to hang.
The task manager reported up to 100% CPU time on a process called csrss.exe.
Resolution:
csrss.exe is an important process in the Windows system and should NOT be terminated, see:
http://www.processlibrary.com/directory/files/csrss/
A known problem can be found in the Microsoft's knowledge base article 555021:
http://support.microsoft.com/kb/555021
Furthermore, the csrss.exe might be cloned by malicious software writers. That said, anyone with a misbehaving csrss should definitely run malware scans, preferably at least two different ones (eg an antivirus utility and an antispyware one).
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csrss is the userland side of the Win32 subsystem. It handles user-mode Windows API and graphics API calls, passing them on to the kernel. Consequently it's a bottleneck (so a variety of performance problems will manifest in it), and it's somewhat fragile. (The infamous "crash Windows by printing backspaces in a command window" exploit a few years back was a csrss bug.)
csrss-related performance problems are a frequent complaint, and there seem to be myriad causes and solutions. An overly-large or overly-full Recycle Bin, for example, can send you to the Pit of Csrss Despair. (On modern drives, the default Recycle Bin size is *much* too large, due to design flaws in the Windows Recycler implementation. Today, around 1-2 GB at most might be a good idea.)
csrss CPU consumption can also be due to poor handling of font metrics in programs that use a lot of fonts (typically word-processing or document-preparation apps, and web browsers and other text-display programs such as PDF viewers). If the machine is used interactively, check what other applications are running.
Some OEM add-on software will drive csrss into a tizzy. Often those add-ons are poorly written and muck about with the OS (eg to change network settings and the like), so they're doubly dangerous.
Some programs that inject threads into other processes (eg ProcessExplorer) or hook system functions (eg firewalls) can interact badly with other programs and cause csrss spinning. Micro Focus does not possess a comprehensive list of the known toxic combinations; this is just something that occasionally people run into.
