Sorry for asking yet another question...
About 50% of the time, I can't jump as high as usual. My jumps consist of me hopping one inch off the ground at most. My double jump does not help. This is inconsistent with levels; I can sometimes jump high in Portal Island, for example, but I sometimes cannot. Usually, going from level to level does not fix it, but when it does, I usually don't have the problem again until I quit.
What should I do?