What kind of engine and tranny? I am having a similar problem on a top loader 4 speed, although mine is when the engine warms up and I come to a stop. Once stopped I have a hell of a time getting it into any gear. When it's cold, there is no problem. I tried adjusting the clutch today to make it a little tighter, but to no avail. I'm thinking maybe the tranny lube is bad, it does move into any gear with the engine off. Good luck with your problem.