Hi, today, Process Guard has asked me if i wanted to allow 'defrag.exe' to run. Since it has never asked me that and since i use DiskKeeper and not the M$ defragmenter, i have answered "block always". And thx to that, i see from time to time defrag.exe blocked from running. First thing we can think of is the scheduler (service enabled indeed) but only the NAV 'NetDetect" task is listed there. I have not allowed nor installed something lately, my AV and TDS3 are up to date, and i'm really confident that my system is clean (i do not use P2P currently too). But now i'm thinking, i have installed the lastest Microsoft critical updates, can it be the cause ? where a modification has been made, and how to remove it ? (no new entries listed in msconfig, no new service enabled). My defrag.exe file information : Size : 69Ko MD5 : BF888C41662F03FFA8242E912513C975 on Windows XP Pro + SP1 Any idea ?