No, no suspicious files, I'm very careful about what I download. The only extension is Ant video downloader for Firefox. I don't remember what I did with the seed, I'm sure I had a text file with the seed at some point but it was stored only on my PC and I deleted it a long time ago or got lost when my old HDD failed. The old HDD never left the house, it's under my desk right now. I only had the old empty wallet which I now wish I had lost too. The wallet was exported on a stick and the stick always stayed in my house. Only I have access to this PC, I'm the only user. I rarely use Google drive, it wasn't ever uploaded there; I went trough all the old emails in my most used accounts and searched for terms and there's no trace of any wallet or seed and I don't remember ever sending anything like that over email in the first place. I don't even use or used Whatsapp, viber or similar apps. I use facebook but never used it for anything crypto related, I didn't have any reason to. I do use this PC for almost everything I do online (mainly youtube watching, wikipedia) including xxx and, rarely, torrents but I did deep scans and couldn't find any virus or malware anywhere. I disinfected dozens of PCs myself in my lifetime, I would've found something if there was something.
I mean it's just 100€ but I'm still bitter about it, I could've used that money.
If you didn't paste your seed somewhere online or some website your seed is safe.
So I'm sure you could be infected there's something blocking the file from scanning that is why the Malwarebytes couldn't find any malicious files inside in your PC.
If the virus was executed and running behind and pretending as system file I'm sure the Malwarebytes can't detect it or any antivirus this most likely a trojan virus.
Did you tried to scan the HDD as external to other PC just to make sure the infected file is not running from HDD? If not do this but make sure that the PC is clean before you scan the whole external HDD.
