How to stop sheet constantly recalculating (could be due to userform)

Hi guys

I have an issue with a large spreadsheet (for footy tipping) and can't solve for it. It was working fine before yesterday, but now it causes my pc to hang as Excel takes 100% of CPU usage.

The problem is most apparent when I open a userform, so I was wondering what could cause the constant recalculation? I know this is happening because I have a cell that generates a random number and I can watch it changing each time the userform is opened.

If anyone can offer a suggestion, it would be much appreciated.

The file is too large to update here and I don't know whether it's the code or functions causing the problem.

Thanks
AussieM8