Monitor randomly goes black for a second every so often

About 2 month ago my monitor
started randomly goes black for a second every so often,
maybe 10 times in 24 hour period.
Connections seem to be ok.
Can not point to any one device that
hooked up to computer, sometimes
when slight mouse, keyboard, table touch
monitor go black for a second, then comes
back.
I have google similar problems, but
no definitive answer.

My comp. 2 years old, power supply 450
and graphic card Radeon 7700HD, built by
brand name.

Tonight I will look inside the computer
for any loose connection.

Meanwhile If anyone could narrow down
what may be the cause of the problem.
much appreciated.

Thank You.

Jack.

Monitor randomly goes black for a second every so often