The Recent Docs menu can be easily disabled by editing the Registry. To do this go to the following Key: HKEY_CURRENT_USER\Software\Microsoft\ Windows\ CurrentVersion\Policies\Explorer. Now in the right pane, create a new DWORD value by the name: NoRecentDocsMenu and set it's value to 1. Restart Explorer to save the changes.
You can also clear the RUN MRU history. All the listings are stored in the key:HKEY_USERS\.Default\Software\Microsoft\Windows\CurrentVersion\ Explorer \ RunMRU. You can delete individual listings or the entire listing.
To delete History of Find listings go to: HKEY_CURRENT_USER\Software\ Microsoft \ Windows
\CurrentVersion\Explorer\Doc Find Spec MRUand delete.
"Windows XP Tips: Cleaning Recent Docs Menu and RUN"
Reference : techpraveen.com