For that last month or so I was experiencing a rather frustrating problem. Every time I opened or created a new file, photoshop would hang for a minute or more before opening the file. I tried all the regular optimization tricks, such as defragmenting my drives, changing the scratch space and doing a memory test, but still no luck. I did search after search to try to find an answer and finally found this forum that contained the answer.
http://photo.net/digital-darkroom-forum/00KCiu
It turns out this happens when your default printer is a network printer that may be either inaccessible or has other problems. I had recently purchased a new router which uses a different local IP and had not changed the network location. Since I rarely print from that machine on my network, I did not notice that the printer was inaccessible. I simply changed my default printer from the network printer to PDF and now photoshop works as it should (quite fast). Seems like a rather odd problem for a well built application like CS3. One would think that it would check for printer issues on launch, and then ignore the printer if none exists, or if it is reporting some issue that prevents it from being properly detected. I am just glad to be able to work at a normal speed again.