Why? If it works accept it.
If you want it chapter and verse download aida32.exe and run that.
If it doesn't work then you may have a problem particularly if it is a SCSI scanner.
My Epson 5500 is SCSI, and old. When loading its driver Windows98 asked me for drivers... etc etc etc. It was best to go all through the motions pressing next until Widows gives up and says it can't find the drivers.
Then quite independantly load the Epson SCSi drivers following the prompts..... later the Application will ask you (under Acquire) for which twain driver you want. Select Twain32, and you are away.
These last few paras are a waste of time if your scanner isn't SCSI but finally....... if it is, you must switch on before loading Windows. You can switch off at any time but blue screen disaster can follow if you plug in the scanner and switch on during a Windows session.