Grinding the gears

I love my s2000 but lately i have had problem. Every so often i will be pulling up to a stop sign or red light and when i go to put the car in first, the gears grind. I know for fact that my clutch is all the way in and this problem has only occured in 1st. I dont know if the synchronizers off or what. Can someone please help me?

Are you stopped all the way when you're putting it into first?

i dont know about the s2000s but almost every honda that i have owned does not like being downshifted into first. it can cause a lot of damage just due to the gearing of the first gear. most manual transmissions manufactorers do not bother putting synchros into first gear as well as reverse due to the fact that the only time one needs to shift into them is from a complete stop when the engine is at a low rpm