Wincache and sessions : "Failed to write session data"

Hi,

Config : Windows Server 2003 SP2 + IIS 6.0 + PHP 5.3.6 + FastCGI 1.5 + WinCache 1.1

I use the wincache session handler ( session.save_handler = wincache ) since the avaibility of WinCache 1.1 on January 2010 without any problem.

This morning I have had a problem. My PHP scripts which create sessions to login to my private interface didn't work while I didn't change anything to this code since several years.

I have restarted IIS (iisreset) but same thing, impossible to create sessions with PHP.

I looked the PHP log file and then I saw the following line :

PHP Warning:  Unknown: Failed to write session data (wincache). Please verify that the current setting of session.save_path is correct (C:\Temp\) in Unknown on line 0 

I didn't change the C:\Temp directory and it is well writable for the IIS users.

Then I have disabled the wincache handler for PHP sessions in the php.ini file (set it to "files") and my sessions work again now. I have then set session.save_handler to wincache and it's rerun fine now....

Any idea what happened ? And Why the restart of IIS didn't solve this crash of the wincache sessions handler ?

Thanks.