Hi,

why not scan the Laptop/PC in question with some AV-Boot-CD ?

e.g. Avast-BART-CD or linux-Defender ?

or even W-Bootdisk, F-Prot-DOS & NTFSDOS-driver ?

P.S.: I’m pretty sure that on any comp something is written somewhere on the disk on fileaccess of exe-files…

by Thumb-drive you mean an USB-Stick ?