+1 An i7 laptop is more than capable to run X3, especially for the things you have mentioned. A lot of the issues suggest "driver conflicts" or system settings as mentioned above. I am unfamiliar with your audio interface, but if ASIO drivers exist they are preferred and a lot of "power management" settings in Windows can cause havoc to a DAW (nothing should ever be allowed to idle, and the laptop should always be plugged in when used as a DAW (when feasible)).
X3 is incredibly stable, so threads like these are concerning. I feel the same as Craig, since I found some cassettes recently of a friend's band and was tracking that from a tape deck into X3 this morning, remasteriing other tracks with Audition (via the Realtek chip on a different sound output), and browsing a lot of stuff on the internet at the same time. In the middle of all of this, I was ALT-Tabbing back to X3 to drop markers between songs on the tracking audio. I am probably one of the more "extreme" users of X3 as I multitask often while using it.
Big longshot here, but this one bit me on X2... did you verify the MD5 hashes of the download files? They are expanded at the bottom of
this page. I had a freaky issue where one file was the proper size but the MD5 was wrong with X2, and it sent me on a "bug hunt" for 3 months which was resolved by simply reinstalling X2 over the previous installation (I did not uninstall it). Also, installs should be done explicitly as Administrator (right click), and virus programs should be temporarily disabled during the installation process. There are similar MD5 hashes for the X3e patch which should be checked as well.