Screen OS

+-----+---------+------- e0/0+-------+ e0/4       +-----+-----+

|   Cisco G881   |-------->|    SSG5     |--------->|    CoreSW 2960   | --------> My PC

+-----+-----+              +-----+-----+               +-----+-----+

                                              |    bgroup0                   | |.....| |

                                              |                            @ @ @ @

                                             V

                                    +-----+-----+

                                    | CoreSW 3750    |

                                    +-----+-----+

The topology of the network is simple as above. There are about 200-300 computers online.

When My PC ping interface e0/0, there are lots of packet loss( some time more than 50%)

but My PC ping interface e0/4, there aren't lost packet loss 

and My PC ping interface bgroup0, there aren't lost packet loss 

Even I ping the ip address of the ethernet0/0, the result is the same as pinging Internet host!!!

So, I believe that there is something wrong with the SSG5!!

 I use the SSG5 as a router and firewall

How much traffic are you trying to pass across the entire device?  200-300 computers seems to be a lot for a device rated at 90-160 Mbps.

Sometime the traffice from Bgroup0 to E0/4 about 70-90Mbps show Many many losts of Packet Loss with SSG5 

i show topo

Ping from e0/4 to e0/0

Ping from e0/0 to gateway internet