Always be concerned with a problem that "solves itself" lol.
One of my concerns is the dual boot. Sometimes, Windows, any version, will act "funky" if the primary ("C") drive is not formatted to that version of windows specs. For example, if your ubuntu partition is Fat32, and your primary drive, but your Windows is NTFS, that could cause the issues you have experienced. (or vice-versa). this issue is not as uncommon as you may think. Soemtimes, it will work fine, others, well, you may have run across the issue. (This is not specific to non-Windows with windows, i experiences a similar issue about 10 years ago with a Dual-boot NT4/Win2k).
The other could be, like mentioned above, driver related. Since that particular model of laptop was designed with Vista in mind. and since Vista was a complete joke, in order for it to work well, the manufactures jumped through hoops. It could be that updating the drivers worked out the kinks, or you silently downloaded a patch.
If the problem recurs, I would, unfortunately, recommend reloading Vista onto the machine and doing an upgrade instead, as much as I hate upgrades, sometimes it is the best way to go, especially from bad versions of windows and the computers made specifically for those versions. (Think "Windows ME" <shudder>)
Good luck!