The clean up command in TortoiseSVN is not working. Why?

Question

While trying to update svn "403 forbidden error" is showing.I am not able to update the project.While entering into each folder i can update. But in one folder again same error occurs.

When a new file added in svn and when i try to update it is not updating in my local copy..

Svn sometimes prompt to execute clean up command.But when clean up is given. It shows:

TortoiseSVN has stopped working

I have seen in many cases that locking may be the problem. I tried releasing the lock, but noting is locked.

I am using TortoiseSVN 1.6.0 and i am using windows7

When clean up is given, it ends up due to below mentioned problem details

*Problem signature:*      Problem Event Name:   BEX   Application 
Name:   TortoiseProc.exe      Application Version:  1.6.0.15855   
Application Timestamp:  49c4da8e      Fault Module Name:    MSVCR90.dll   
Fault Module Version:   9.0.30729.4926   Fault Module 
Timestamp:  4a1743c1    Exception    Offset:    0006c955   Exception 
Code:   c0000417    Exception   Data:   00000000   OS 
Version:    6.1.7600.2.0.0.256.4      Locale ID:    1033   Additional 
Information 1:  3721     Additional
Information2:   3721b00010d0d8c722df055a03e879e0   Additional
Information 3:  0b39    Additional Information
4:  0b391ced731efbba00379ff9de0b1dcd

By deleting the particular folder and adding again solved update issue.But still Clean Up is not working