Update: Looks like I am not doing anything wrong here. When I execute a thread example, it works fine. I am not sure, then why am I getting those errors when I start Apache.
Check your PHP's compiler version using phpinfo() as you have already done. Mine and your both is VC9
Download and install proper Pthread package that matches your compiler version. I downloaded "php_pthreads-0.0.45-5.4-ts-vc9-x86.zip" file. Make sure your OS version also mathes (32-bit or 64-bit).
Extract Zip file in a temp folder
Copy php_pthreads.dll to the 'bin\php\ext\' folder
Copy pthreadVC2.dll to the 'bin\php\' folder
Copy pthreadVC2.dll to the 'bin\apache\bin' folder
Copy pthreadVC2.dll to the 'C:\windows\system32' folder
Open php\php.ini and add "extension=php_pthreads.dll" without quotes at the end of file
Restart server and you won't get any error message.