Are u dasiy-chaining ur peripherials to a single wall
socket?
i.e. One wall socket, u connect
1.) PC
2.) Printer
3.) Speakers
4.) Hi-Fi
5.) TV
6.) Fridge
7.) etc.
If yes, just isolate only ur PC and ur speakers (i.e. only switch
these 2 on) and see if the 1st problem still exist or not.
If still have, isolate the 2, one wall socket to PC, one wall
socket to speaker.
(u might need extension wire for this test).
If dun have problems liao, simply means either ur PC or ur speaker
is drawing too much power and requires and individual wall socket
for usage.
If still have problem, use another speaker and test under isolate
conditions (i.e. 2 wall sockets). This will isloate the problem
down to the speakers or the PC.
I can only recommend until here, anything down to PC or speaker
level will require a technical person to be on-site liao.
Just my recommendations