Autocad lag after not being used for a while

Hi, I am continually having problems with Autocad lagging if it hasn't been used for a while. I am running Windows 7 64bit 12g ram. This has occurred with Autocad 2011 and 2014. using Resource Monitor I can see the harddrive being accessed repeatedly by; C:\Programdata\Fleznet\adskflex_00691b00_tsf.data and massive amounts of: \Device\harddisk0\DR0 This creates an enormous amount of lag unit this activity clears. This can either be 1min or up to 10min. I have scoured the internet but have never been able to find the problem. Changed graphics cards,drivers,ram etc updated to Autocad 2014 but no change. Any ideas welcome Cheers Steve