Error keeps popping up

Hello, My friend ask me to help him with a error that keeps popping up every time he tries to create a server,error like Model models\weapons\w_pist_p228.mdl has a bad texture models/weapons/w_models/w_pist_p228/w_pist_p228
Model models\weapons\w_smg_mp5.mdl has a bad texture mode
please help.Thank You