The number of posts about Explorer hanging up or running as fast as molasses in New England Winter at night is well discussed. It's all about Explorer trying to render thumbnails or more.
Some find setting the view to details can help. I find that using other file browsers like Gyula's Navigator to side step having to cure this on every machine you have to use.
If these are VIDEO files I eventually have to research what CODEC is used in the video files and see if those need updating. It's a shame that MSFT didn't consider this a bug.
I have recently upgraded to Windows 7 and have noticed when using windows explorer that going through my file system,things have been slow in loading. I have also had problem transferring Digital Juice preview files from my dvd drive to the hard disk,in the middle of the transfer, things bog down and eventually the software stops responding.
I have more than adequate amount of RAM (4 gigs) and storage and am running two dual processors as well as a decent nvidia video card.
For the most part eveything else seems fairly normal. Not sure where to begin?