Cannot pick up grenades

I am having a problem in half-life. When I first came to grenades, levels far below, I was able to pick up the 1st 1 or 2. Later, when I went to use them I noticed that the entire 5 area in weapons selection is just a red box. When I press 5 I just get a DOINK sound (like when I press 4, where I have no squares, red or white). Now when I find grenades I am unable to even pick them up. I 1st installed the game off a CD my father-in-law burned, but ended up buying the Adrenaline pack. I never reinstalled because it all worked, until now that is.... Any help without un- and then re-installing?

Hey I am new to this however, you have to run into the grenaded, you can carry maximum of ten grenades at any time. IF you have ten grenaed you wont be able to pick up new ones. And if you haven't then you can.
I hope this helps

Smokey

actually, what happened is I had to install the patch. I also found out that when unpatched my energy level was never increasing and not protecting me at all. Now I am patched and it is all good.