Hi Magic Andre, Sorry to bother you. I think my prefetch on windows 7 ultimate x64 is doing strange things. Basically I ran your optimisation a few months back and it worked well. My boot got a bit slower over time, so a few days ago I went into windows/prefetch and deleted only the .pf files to rebuild the prefetcher. I only did it this way to avoid the lengthy 2nd part of the optimisation due to a lack of time. Anyway all seemed fine, subsequent boots were a tad quicker. That was until the 6th or 7th boot after this. It was as if something happened & prefetch was no longer working/ or corrupt. No error messages but my boot suddenly increased by over a minute. 7 or 8 boots later and still it was slow. So I ran your optimisation and it all seemed to be ok again. However, yesterday there were some windows updates which I installed and as a result the boot immediately slowed rapidly again despite constant reboots (about 8 in a row I tried). So I deleted the pf files again from prefetch folder. Instantly the boot sped right up until, yep you guessed it, the 6th or 7th boot when it slowed right down again. Very odd??? So late last night I ran your optimisation again. At first it errored as it had to wait too long for the prefetcher. I deleted the pf files again and after doing this your optimization ran through just fine. And since then (some 8 boots after running it) my boot has been okay again (about 100ms according to event viewer which is about normal/peak for my laptop). Has my deleting the .pf files caused my problems? I only deleted these and not other files in that folder. Also I wasn't emptying them from the recycle bin (until the last optimisation) so I wonder if this caused part of my problems. So at this moment in time my boot is fine but i worry as soon as I install another windows update or any other type of program the problems will come back? I am worried my deleting of the pf files in the prefetch folder has caused all my issues? Should I have deleted the whole folder including the readyboot sub folder when i did it? I kind of wish I'd never touched it now! I was under the impression deleting the files would cause Windows to rebuild it. Many thanks, Wayne