Solution : https://service.sap.com/sap/support/notes/940122 (SAP Service marketplace login required)
Key words : 
uninstall db2 udb v8 fixpak 11, {d8f53726-c7ad-11d4-9155-00203586d551}, uninstall v8 fixpak 11, installed db2 product, add/remove programs, backup file xxx, file disableca, windows platforms, system issues, script disableca
Related Notes : 
       
| 603981 | DB6: Installing V8.2 FixPaks (as of FP9) on Win NT/Win 2000 |