Hulu programs stop and screen message says I may have to clear my browser cache. Does this sound reasonable? How do I do that?
Tools > Options > Advanced > Network (tab) > "Clear Now" (button)
I don't use Hulu, so I don't know whether clearing your cache will help...
You can open the Options dialog from the orange Firefox button or the Tools menu:
Options dialog > Advanced > Network > Offline Storage: "Clear Now"
Or you can use
Tools > Clear Recent History
but take care not to clear other history you want to save.