ModMii has an emulated nand builder which does not create the cert.sys. If you however extract a copy of your nand with Giantpune's Wii NAND Tools, ShowMiiWads or Simple FS Dumper you should get the cert.sys file.Just out of curiousity, why do you think this file was missing? How could that have happened?I figured out the problem is caused by a missing cert.sys file from SYS folder.Testing R27 - again I get Wii system files are corrupted...blablabla whenever I run wiiware from emulated nand (same settings as before) no matter what setting or IOS I use.
Any news about this problem?
Copying the file just fixed all nand emulation issues...