Check out Getting “As” Right by rogersgeorge. Here is an excerpt:
People sometimes use “as” when they mean “because.” Well, don’t. Use “because.”
“As” means something like “at the same time as,” and here’s an example of how “as” should be used:
Now the company has removed a link from its download site, and updated a support page to say “We have paused…
The full article is available here.