HP LaserJet 1100 All-in-One Printer series - Manual (Page 109)

EN Finding the solution 99
The scan takes too long
Do you have your resolution and gray scale set too high?
Having the resolution and gray scale set high will cause the scan job
to take longer and will result in larger files. Scanning or copying with
the correct resolution and gray scale settings for your job is important
to obtain good results. To learn more about resolution and gray scale,
see “Scanner resolution and gray scale.”
Did you send a print or copy job before attempting to scan?
If a print or copy job was sent before attempting to scan, the scan will
occur after the other job is finished.
Is your printer set for bi-directional communication?
See the documentation that came with your PC to change bios
settings.