Cisco 3750 stack switches

[svadmin2009]

I have a stack  of four Cisco 3750 switches,  lately the switch stack is behaving funny, it is jittery, very slow and when I ping it is dropping packets at least 1 out of 5 packets. I see nothing on the log, CPU usage sometimes reach 100% but not very often, average below 10%, no error or packet drops on the interfaces. Can any one help?

[devils_advocate]

What are you attempting to ping which shows you packet loss?

If you ping between hosts connected to the same stack, do you get any loss or high latency?

What IOS are you running?

Thanks

[svadmin2009]

Thank you for replying promptely.

Any host from the switch to the LAN and to WAN.

GS1SW#ping 10.1.35.201

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.35.201, timeout is 2 seconds:
!!.!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/1 ms
GS1SW#ping 10.1.41.163

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.41.163, timeout is 2 seconds:
!!..!
Success rate is 60 percent (3/5), round-trip min/avg/max = 1/1/1 ms
GS1SW#ping 10.1.40.81

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.40.81, timeout is 2 seconds:
!!..!
Success rate is 60 percent (3/5), round-trip min/avg/max = 1/1/1 ms
GS1SW#ping 10.1.32.26

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.32.26, timeout is 2 seconds:
.!!.!
Success rate is 60 percent (3/5), round-trip min/avg/max = 1/1/1 ms

GS1SW#ping 10.5.10.21

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.5.10.21, timeout is 2 seconds:
!.!.!
Success rate is 60 percent (3/5), round-trip min/avg/max = 9/11/16 ms

The switch stack is running ios Version 12.2(25)SEE3

[devils_advocate]

Are you noticing any issues from a client perspective, i.e hosts connected to the switches?

Can you ping from host to host, what results do you get?

The switch stack is running ios Version 12.2(25)SEE3

I would get the IOS updated also, I think the latest is 15.x

Thanks

[svadmin2009]

don't see any packed drops when ping test done from a host to the switch or through the switch.

I do not have cisco support to upgrade the switch to the latest version.