It can be that your PC video resolution is set higher than 1024 x 768 @60Hz for the monitor to display correctly.
Try this per HP:
HP Business Monitors - What Do I Need to Do When the Message Sync out of Range Displays on the Monitor?
What do I need to do when the message Sync out of Range
displays on the monitor?
When the video card signal exceeds the frequency allowed for the monitor, the following error message may occur:
Sync out of Range
To avoid the message, lower the resolution or vertical frequency of the video card.
Reboot the system and use the VGA mode to force the video card driver to lower its resolution. Follow these steps.
Shut down and restart the system.
For consumer systems such as HP Pavilion desktop PCs, push the Power button once.
For commercial systems such as HP business desktop PCs, hold down the Power button for five seconds.
Immediately after seeing the HP/Compaq logo screen, press F8 at system startup to initiate the bootup menu.
Scroll down to highlight Enable VGA Mode , and press ENTER .
After Microsoft Windows completes its bootup process, access the Display Properties and select a desired resolution, which is compatible to the connected monitor.