General :: Android Malware Randomly Downloading Files

My mother has an Asus Transformer, and she's had it for awhile, but she doesn't use it for much other than getting e-mails or video chats. I turned it on today and it suddenly downloaded a bunch of files. Mahjong.exe, Bubble_Hit_brch.exe, 7-superfoods-to-boost-your-immunity.pdf, etc. Small files, less than 1MB per file. There were about a dozen files in her downloads folder, a few of which had "-1" after it so it had downloaded some of them twice now.

I've Googled the filenames, Google "downloading files at random", "downloading unwanted files", etc., etc. I installed three different virus scanners and they found nothing. I believe her when she says she doesn't download anything or install anything.