My bet is on the wall flashing which is behind the siding at the gutter area. This area always gets installed incorrectly.
This is a pain in the neck job to fix.
Remove the gutter.
Remove the siding with a "zip tool" which is a vynil siding removal tool.
And you will see if the wall flashing , called Step flashing, is installed so the water does not run behind the paper . (TYVEK)
Then install what is called a Kick out flashing for the bottom piece of wall flashing, so when it rains, the water kicks back out into the gutter, not behind the siding paper.
Hope this makes sense, but this is the problem, 99% of the time.[
Try this link to see the issues involved.
url=http://www.kickout.info/gallery.html]Kickout Flashing Gallery -
www.Kickout.info - Another great official website from Michael Leavitt & Co Inspections, Inc.[/url]