Lanky,
The more electronic equipment you have on this circuit, the more ''natural'' leakage is going to be present on that circuit. As Chris stated, most if not all electronic equipment make use of supply filters and the like, to protect the sensitive electronic components. It could be one such units filter(s) is breaking down allowing more leakage to flow on the affected circuit.
If you have an RCD that is looking at the whole of your Consumer Units circuits, then the more prone to this type of tripping your RCD is going to be, as it's seeing the leakage currents of All the circuits. Even on split CUs where two RCDs are protecting several circuits each, this can still be a bit of a problem. The only real solution is, individual circuit protection by using RCBOs, but that can be expensive....
You may just have a particularly sensitive RCD, that is tripping far below stated sensitivity. The only way to be sure of what's happening in your installation, is to employ a qualified electrician to undertake the relevant tests on the leakage currents present in your homes installation.
