/tmp folder on the server keeps filling up

I received an email from my web host that they have suspended my account because “The /tmp folder on the server keeps becoming filled and, upon investigation, we identified you were using nearly 50% of the storage in /tmp.”

The file names look like this: phpZeBuBI

The host put one of the files in my root folder for me to look at. It’s a text file that keeps repeating:

“INSERT INTO wp_posts (ID, post_author, post_date, post_date_gmt, post_content, post_title, post_excerpt, post_status, comment_status, ping_status, post_password, post_name, to_ping, pinged, post_modified, post_modified_gmt, post_content_filtered, post_parent, guid, menu_order, post_type, post_mime_type, comment_count) VALUES”

with various file names and info underneath. Near the bottom I noticed some names of advertisers, products, and spam in general.

The plugins I have installed are: Akismet, Contact Form 7, FD Feedburner plugin, google xml sitemaps, hyper cache, print friendly and PDF, Shareaholic, Social Media Widget, Tweetily, User Avatar, WordPress Backup to Dropbox, WordPress Popular Posts, Yet Another Related Posts Plugin

I haven’t installed any plugins in the past few weeks, and prior to that the latest one was the WordPress Backup to Dropbox.

Could someone please help me? I don’t know what to do – the host has temporarily allowed my site back up, but I have to fix it immediately.

Thanks in advance!