Using Chrome on Windows? There’s a good chance you’re still using the 32-bit version. You should upgrade to the 64-bit version. It’s more secure–not to mention faster and more stable.
The only reason not to upgrade is if you’re using a 32-bit version of Windows that can’t run 64-bit programs, but most computers built in the last eight years or so should be 64-bit compatible. Even if your computer is compatible, though, Chrome won’t update to 64-bit on its own–you have to download it yourself.