Weird Issue

[dae314]

At one point when playing snowboard kids 2 on project64, I encountered a program freeze. I stopped project64 and restarted it and it happened again. I restarted my computer then started project64 and snowboard kids 2 again and this time it ran but there were certain things missing. For example, the start menu items couldn't be seen (start game, options, etc) and the shop items were also invisible and when choosing a stage, the background was wrong. I later tried to start star fox 64 and this time the start menu items had no words and when I started the game I couldn't see my shields or the picture and that appears on the bottom when somebody talks.

I uninstalled and reinstalled project64 and it seems to be working now, what did I do wrong the first time? How can I prevent this from happening again?