One of my V6 boxes after a reboot is fine for two or three days then when you press remote things seem to slow down and lag until a reboot and it starts again . Think my boxes must be 3 years old now .I'd rather find solutions and workarounds than to be constantly calling virgin for replacements .
Sorry to hear you're having issues again with your V6 box still. If you have tried clearing your suggestions as mentioned in your previous post, I think it also may be time for a replacement box if you are still having issues.
Can you check if your hard drive is almost full first? Once the hard drive is almost full, it can cause the box to slow down a bit.