[comp.sys.ibm.pc] Strange lines on I.B.M monochrome monitor

CHIGGS@oregon.uoregon.edu (Colin Higgs) (12/22/89)

Help !

I'm running a genuine IBM AT with a Hercules graphics card - up til now
it's been running just fine.  Today on boot the screen is FILLED with
narrow vertical lines (a guess, but about 50 of them) on top of which
all of the DOS text is visible.  When I load some programs, eg. word, excel
I get perfect screens.  What should I look at first?  Lines appear
immediately when I turn on the computer - before it goes out to DOS!

Thanks for ANY help