upgrade 7.5.1 to 7.6.1 issues

[rranieri]

Hi

I upgrade my box from 7.5.1 to 7.6.1

After change CP from apache to IIS 6.0 this error message appear in CP login screen:

Warning: There is not enough space on the disk. (Error code 112) at Open file 'D:\Plesk\/admin/sessions\Session_cbfcbc522841c5ac9350f7c0410630f5' in Unknown on line 0

Any sugestion ?