Tempo slowing and crackling

Disco1438

Having used my S4 Mk3 twice now, ive experienced an issue which i don't know how to solve and hope someone can help please.

After the S4 Mk3 has been running for some hours, it seems to slow the tempo on both decks and have a crackling sound come through the output. If i change tracks it makes no difference. The only resolve currently is to shut the programme on the laptop and start it up again. Initially i wondered if this might have been due to a windows update, but all updates were done this morning. This has happened both when connected to wi-fi and also when not connected.

Please help, this is getting worrying and i don't want this to happen during a gig.

TIA