พอดีผมได้ลองแก้ปัญหาให้เพื่อนคนนึงที่ไป update SP2 ของ window XP
ปัญหาคือหลังจาก update แล้วไม่สามารถ login ได้โดย error ดังนี้
"The program issued a command but the command length is incorrect"

ผมเลยไปเจอวิธีแก้มาดังนี้ครับ

I've found two solutions for fixing the error "The program issued a command but the command length is incorrect." that seems to be caused by KB885835.

Solution One:
Reboot and hit the F8 key until you get the bootup menu. Select "Last Known Good Configuration". Once you have logged on immediately do a "System Restore" to a time before the updates were installed. Reboot. Then go back to http://windowsupdate.microsoft.com/ and install all updates yourself.

Solution Two:
If for some reason you can't do the previous method of using system restore you can use a Windows XP CD (Original, with SP1, or best: SP2). Insert the install cd, reboot and during the setup questions it will ask you if you want to repair the copy of windows already detected. Do that. It will then reinstall windows in repair mode so nothing will be lost on your computer. After windows has been "repaired" you can then just go to http://windowsupdate.microsoft.com/ and install the updates manually and everything will be fine.