Have you considered the possiblity that the package you've downloaded is corrupt?
We'll need more information than this. What installation method are you using, is your memory card a genuine Sony one, which version of uLaunchELF are you using, where did you get the installation files, what is your PS2 model etc. - provide us with more detail.
Memory cards are a little bit slow sometimes - disregard any lag.Okay, it booted, all good. Thanks. I'm curious though, how long does it usually take to check for available space on the memory card, do you know?
EDIT: Never mind, everything is a go!