> Could you please post more info?
>   
oh, yes of course sorry.
> - What version did you try? (3.0 release or -current HEAD?)
>   
I want to install 3.0
> - Did you edit partition on sysinst menu?
>   
yes and no, I tried both. First I created my custom layout. But because 
it doesn't work, I take the default.
As I already say, moving the partition A to start with an higher 
cylinder number, doesn't help
even with a unused partition A the same error came up.
> - Could you show disklabel output?
>   
sure, with the default layout:

# disklabel sd0
# /dev/rsd0c:
type: unknown
disk: mydisk
label:
flags:
bytes/sector: 512
sectors/track: 161
tracks/cylinder: 5
sectors/cylinder: 805
cylinders: 5172
total sectors: 4163460
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

8 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:   3900225       805     4.2BSD   2048 16384 23112  # (Cyl.      1 
-   4845)
 b:    262430   3901030       swap                     # (Cyl.   4846 
-   5171)
 c:   4163460         0     unused      0     0        # (Cyl.      0 
-   5171)


my own config:
8 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:   1433705       805     4.2BSD   1024  8192 44808  # (Cyl.      1 
-   1781)
 b:    262430   1434510       swap                     # (Cyl.   1782 
-   2107)
 c:   4163460         0     unused      0     0        # (Cyl.      0 
-   5171)
 d:   2466520   1696940     4.2BSD   2048 16384 22560  # (Cyl.   2108 
-   5171)


> - Did the error happen during sysinst?
>   Or did you try disklabel -B manually?
>   If so, was partition a mounted at that time?
>   
This happened during sysinst, but also manually. Because it doesn't work 
with sysint I tried to disklabel on my own.
> Last time I tried install 3.0 on my hp425t
> (when I noticed bootloader botch on fb console),
> bootloader was installed properly.
>
> In -current, hp300 MD part of sysinst has been modified to
> create an independent FS_BOOT partition to avoid confusion.
> (i.e. partition c should be a raw partition)
>   

I will try this later.

Best Regards
Stephan