Thanks MSFN Addict for your efforts to help. i did try that R171788.exe file last week but it would not install on my E520, and the two updates KB937287 and KB938371 are installed, and it would not install prior to the KB937287 or after. I received a another email Monday from the Microsoft Windows Support Professional 1. Restart your computer and start pressing the F8 key on your keyboard. On a computer that is configured for booting to multiple operating systems, you can press the F8 key when you see the boot menu. 2. When the Windows Advanced Options menu appears, select Safe Mode, and then press Enter. 3. Log onto Windows by using the Administrator account or any user account with the Administrator privileges. NOTE: In Safe Mode, your system display and Desktop will look and perform differently than in Normal Mode. This is only temporary. To return the system back to Normal Mode, we can simply restart the computer. Step 3: Use the System File Checker (SFC) ================================= 1. Click Start, type "cmd" (without the quote) in the Start Search bar, right-click cmd.exe and click run as administrator. 2. Input the following commands and press Enter after each line. sfc /purgecache sfc /scannow Note: There is a SPACE between "SFC" and "/Scannow", "/Purgecache". This command will take several minutes to complete. Step 4: Windows Vista Memory Diagnostic Tool ================================ 1. Click the Start Button, and then type "memory" (without quote marks) in the Start Search box. 2. At the top of the Results box, click Memory Diagnostics Tool. 3. When the tool opens, click Restart Now and Check Problems. The computer restarts and the diagnostic program starts. Please let me know if any error is detected by the above steps. ==================== Both procedures were done, although i had to run the Memory Diagnostic from the .iso as it could not run at boot (others have this problem, likely to do with dual booting). No errors were found, and SP1 still will not run. I also have tried running it with just basic services, and my XP drive unplugged, or with audio uninstalled and disabled in the bios, and SP1 is still a no go. i could reinstall Vista, as the whole c partition is recently backed up, but i am not sure that would do it. I'll wait to see what the Windows techie can suggest. Meanwhile i use XP most of the time, as i find it faster. Thanks for any suggestions.