google crawl report issue - 2 questions!

[Billmcq]

I hope an expert or two can help shed light on this issue.

I run a real estate website and use an idx plugin that genreated thousands of pages. I have experienced a severe drop in rankings this past week, and through investigation, I came across this.....

QUESTION1:
I have about 30,000 pages in the Google crawl report that indicate a 404 error. The 404 is coming from what appears to be an extra "ar" in the links. ALmost all these links are IDX generated pages (property pages), but not all. I actually found one that has nothing to do with the IDX, and is actually just a link to my blog. The permalinks are set correctly with a

/%year%/%postname%/

.

http://www.websitename.com/ar/category/blog

Any idea from some experts out there what is causing this extra "ar" in the link?? it is found nowhere on the actual site. It appears in both idx plugin generated pages, and my own pages as well.

QUESTION 2:
I have a few of these in the crawl report as well

http://www.wesellsarasota.com/2009/cascades/undefined?789

Where is the undefined?789 coming from? I have it on a few different pages, but when I go to those links on my website, the links work fine.

Any insight would be very helpful!!