MicroSD card stuck after CMD8, responding 0x5 before next CMD is issued

I have a problem for which I can’t find the solution in previous topics.

I’m using a microcontroller to read data from a Kodak 2GB Micro SD Card. I want to write a minimal driver in SPI mode, no need to do writing or formatting operations, just read some files.

I can see those signals on a 4 channel scope: CS, MOSI, MISO, CLK.

I do the following:

1. I send 100 bytes at 100KHz, with MOSI and CS high.

2. I send CMD 1, no argument, response type R1 returns 0x1, correct.

3. I send CMD 8, arg=0x1AA, response type R7 returns 0x1+ arg 0x1AA, correct.

4. At this point every command returns 0x5 at the 4th byte of the command. In other words, before the 6 bytes command is completely issued.

Any explanation for that?