Posted by Embusqu3
Go into your scripts folder in the cstrike directory. Then go into the folder titled 'Weapons'. There will probably be a script called p90. Weapon scripts in this folder normally tell the weapon what sounds to use, and any other neccessary commands. If you've had a previous p90 skin, it probably had new sounds, that had different names than the default sounds. Because these new sounds are named differently than the default, the weapon requires a script to tell it to use these sounds instead of the default.
Long story short, if you see a p90 script in the cstrike>scripts>weapons folder, delete it. If you don't have a p90 script in that folder, then I really don't know what's wrong, and I'm sorry I was unable to help you
There aren't script folders in 1.6 or cs:cz as far as I know.