I have a D505 and I had the same problem with 3.9 and 4.0 until I installed 4.0 to the hard drive then the screen resolution problem went away. Note that I like 4.0 a lot but its a little buggy.
Knoppix 3.7 works very fine on my notebook, but the 3.9 not.
Every time I boot it, the resolution is always 640 x 480 and I can't change it.
Any suggestion ?
I have a D505 and I had the same problem with 3.9 and 4.0 until I installed 4.0 to the hard drive then the screen resolution problem went away. Note that I like 4.0 a lot but its a little buggy.
I've been having trouble with v 3.9 on my d505 also. I get an x-server error during boot up.
I have tried some of the cheat codes and also seen some posts that suggest that the x-server error may be due to a flaw on the CD.
I'll keep digging for an answer.

Fortinet FortiGate FortiWiFi 80F Network Security Firewall (FG-80F)
$83.99
Zero Trace Pen: All-in-one Tor Network Anonymous Drive + Cryptocurrency Wallet
$147.00
Untangle z12 NG Firewall Server Caswell CAR-3070
$329.99
Cisco ASA 5506-X Network Security Firewall Appliance- No Adapter
$50.00
Palo Alto PA-220 Next-Gen Firewall 520-000309-00J
$40.00
Sophos XG 135 Rev.2 Next-Gen Firewall | C1226*
$49.99
Fortinet FortiGate 60F FG-60F UTM UTP License Until 2027 Network Security FW VPN
$299.99
CloudGenix ION 3000 Firewall / Network Appliance
$100.00
Palo Alto PA-440 Next-Gen Firewall PAN-PA-440 GREAT WORKING CONDITION
$274.99
SONICWALL TZ370 NETWORK SECURITY FIREWALL APPLIANCE VPN 8 PORT GIGABIT ROUTER
$95.50