Stuck in gears

[paulheymeson@xxxx]

Hello list,

About 4 weeks ago I was driving along normaly,changed up from 3rd to 
4th gear although no it was stuck the shifter was like solid.
So i pulled over to the side of the road engine off let clutch up 
then down and everthing returned to normal.Untill-
Today I expirenced the same problem but it happened 4 times on the 
way home from work (20 mile trip)sometimes I was stuck in 1st gear 
sometimes 2nd when I tried to shift and it did the gears crunched!
But everytime I stopped waited switched off and then set off again 
everything was fine for about another 5 mins and so on 3 more times 
same thing.
Any suggestions please,by the way I have had a new clutch fitted and 
clutch fork only 5,000 miles ago.

Thanks Paul UK