Having this problem since getting my laptop from SP.
Once in a while,after i log in to my account, even though
there's an instance of explorer.exe running - there's no explorer
no nothing.Only the wallpaper can be seen.
When i open Task Manager,very few process are running.

The cmd.exe,Task Manager and Msconfig were initiated by me.
Even if i terminate and re-initiate the
explorer.exe,nothing happen - only after a few minutes then the
explorer.exe finally load up to normal state.
Not sure if another problem is related,but i noticed that during
the time of the error,there was an error with automatic enrolment
as seen in the Event Viewer - "Automatic certificate enrollment for
local system failed to contact the active directory
(0x8007054b). The specified domain either does not exist or
could not be contacted.
Enrollment will not be performed."
Can anyone help me?The SP Service Centre cant do anything but
reformat,but i do not want that as the other time i sent in my
laptop for reformatting(seperate problem),the problem already exist
prior to the reformat so im certain reformatting wont solve the
problem.
That said,im sure its not my programs nor adware causing the
problems because my laptop did not had the exact same data(programs
etc) before and after the first reformat.
I think its a problem with a process that load very slow?