There's no single answer, but if you can see the hard drive "thrashing" during this period, have a look at it:
- is it nearly full? If so, try deleting some stuff, and run "cleanmgr" to see if there are temporary files you can clean off.
- See if you need to defragment: run "defrag /a" or select "Defragment" in the Disk Properties, then the "analyze" button.
You need >15% free space to defrag, so if you need to free up space for defragmentation, you can:
a) stop Hibernation and delete the HIBER.FIL (?) file in C:\
b) on System Properties / Advanced, temporarily turn off Virtual Memory (Pagefile) & reboot. Re-enable Virtual Memory after defragmenting.