Site Goes Down Frequently, While Server Is Still Up

This is the Strange problem i face. my blog goes down while the server is up, comes back automatically after some time.

I can access the Cpanel without a problem, can anyone tell whats wrong?

Code:

C:Documents and SettingsGaurish>ping [url]
Ping request could not find host [url] Please check the name
d try again.

C:Documents and SettingsGaurish>ping [url]
[url][67.228.104.181] with 32 bytes of data:

Reply from 67.228.104.181: bytes=32 time=495ms TTL=50
Reply from 67.228.104.181: bytes=32 time=468ms TTL=50
Reply from 67.228.104.181: bytes=32 time=500ms TTL=50
Reply from 67.228.104.181: bytes=32 time=515ms TTL=50

Ping statistics for 67.228.104.181:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 468ms, Maximum = 515ms, Average = 494ms
During this i don't change any setting, so less chance misconfiguration