IFR2975 keyboard error

[kf4eok]

When I boot my Areoflex IFR2975 it comes up with a Keyboard error or no keyboard present.

Press F1 to continue, or DEL to enter SETUP

I have a PS2 keyboard plugged into the lower port on the back of the unit just below where I have the mouse plugged in.
Once I press F1 the unit boots as it should and operates as it should.
Is there a way to get rid of this error? Do I need a different keyboard for this unit?
Thanks for any ideas to resolve this error.

[VE2VXT]

Hello Daniel,

One of our test-set in the shop react like the one you have.
Did you found something?
I've tried to connect a USB keyboart with an adaptor and nothing happen.
Hit the help button help to start booting but stop somewhere before the end.

Thanks
Eric