Monitor loses signal, only reboot helps. Why?

Question

Iron

There is a monitor, and if you slap the table next to it, then interference appears, if you hit harder, the image disappears (everything looks like the cable from the computer is disconnected). And during the work we walk around him on tiptoes) It is impossible not to stomp, or touch the table - the signal disappears. Reboot helps, sure. To make sure this happens, you need to compress the top edge of the monitor. The decision is of interest not because the monitor is important (it's an old Samsung SyncMaster 151S), but from a technical point of view, it's terribly interesting why this happens.

Answer 1

Cold soldering (cracks) on VGA connector or any other.
In general, "non-contact"

Answer 2

Why this happens, only the radio master can tell you, and then when he opens the monitor and makes at least a superficial diagnosis of the components.
Anything can be found. From the banal circuit of tracks / contacts from many years of dust, to the failure of radio elements, for example, swollen capacitors on the power supply.

Answer 3

Start by replacing the VGA cable, which you can take, for example, from a nearby working monitor. Helps in 80% of cases approximately.