New Pages Not Staying In Index After Server Change

[riospace]

I upgraded my server 3 months ago. My old server was getting overloaded and I thought this new server would do wonders for my sites speed etc. But, unfortunately, everything has gone down hill since upgrading servers.

The night that I was transitioning to the new server, Googlebot showed up and I recieved a 5xx error for one of the main sections of my site. Since that night of the change over, my numbers suddenly dropped from 60,000 uniques/day to 17,000 uniques/day and has not come back up. My pages that were already indexed have dropped down in the search results and non of my new pages are being index in the section of my site that recieved the 5xx error. I have created Google sitemaps etc. and nothing seems to be helping.

Three times since the server change 3 months ago I noticed that the new pages where indexed, but only for about 1 day and then they disapeared again.

Any suggestions?

[WiseWebDude]

REally we would need more info to help. What changes were made AFTER the change? 301s done? ALL the info you can provide would help. How many sites do you have, etc..?

[riospace]

Only one site and no 301's or domain changes of any kind. The only change was my IP address and physical server.