Hi Capper Neil,
It is most likely a case of a minor software confliction that is causing this issue to occur, I recommend you reset the GSII to resolve this issue. You can reset the device by going to Settings->Backup->Factory data reset.
Please note you will lose all applications and saved data, including your Google account, so ensure that you back up your device prior to performing the reset. If this issue is still there after a reset, I would advise that you take your GSII to a local service center.
If you would like to check for service centres by postcode, please click on the link below and choose ‘Mobile Phones’ from the drop down menu:http://www.samsung.com/uk/support/l...