Problem With Skype

[tearinghair]

For the first time since I exchanged my desktop for a laptop, I tried to Skype yesterday. My contact wasn't in fact online, but when I attempted to make the call my screen was dreadful, full of what I can only describe as strawberry-coloured swirling snow. I'm not a pretty picture at the best of times, but this exceeded all previous horrors. I tried also on my tablet, where the picture was clear. What might have caused the problem, and is there any way of improving things before I try again?