Vista and The optiplex 755 are not supported as a server. If it needs to be on 24 x 7 then disable hibernate as well as any other power saving. Using as a "server" means you will have to reboot often cuz microsoft windows is a horrible server. The fact that you are using 32 bit windows means you arent using 8 gigs of ram for the "server" another problem because windows is junk and gobbles up memory with various memory leaks.
With all the logging and swapping on the SSD you will chew up and destroy the SSD in no time.
This is not a Dell issue and This forum is not "server support" for a system that is not validated as a server.
You could try 64 bit windows server 2011 which is around $50.
Support for that is also not available from Dell.
Microsoft Windows Home Server 2011 64-Bit
www.microcenter.com/.../Windows_Home_Server_2011_64-Bit_OEM_W-_10_CALs_PC
Windows Server 2012 Essentials is $500 and support for that is more $$$$
http://www.neweggbusiness.com/Product/Product.aspx?Item=N82E1683241657