how to change existing logo in SAP which has already been edited

Dear All,

I've been given the task of changing the logo on the SAP logon screen. i know the steps to do it...going to SMW0, changing MIME editor etc.

My problem is: that there's an edited logo already existing which is on display. i've found out the name and it is visible in the SMW0. i've gone to settings-->Assign MIME Editor

and have done setting: MIME TYPE: image/bmp; Editor: C:\Windows\System32\mspaint.exe

after saving this setting, when i click on that particulat obj. name and click on disp or change, it displays following message:

c:\windows\system32\~wwwtmp.bmp was not found

nothing else happens!

where am i going wrong...what should i do...please help.

Regards,

Tejasav