Earlier this week, we reported that Ask.com Crawler Inserting Url-Encoded Spaces in URLs Causing 404 Errors. In short, Ask.com's crawlers were crawling badly formed URLs, causing tons of 404 errors in web server log files.
Vivek Pathak, Ask.com's Infrastructure Product Manager, replied to the WebmasterWorld thread saying Ask.com has fixed the issue.
We did experience a data error which caused us to crawl badly-formed urls from a small number of sites. We identified the issue and corrected it on Dec 29th. Thanks for flagging and please let us know if you see any further problems.
Webmasters in the forum have confirmed that they are no longer seeing 404 errors produced by Ask.com's spiders (Teoma).
Forum discussion at WebmasterWorld.