after dban on hd and a successfully installation unable to boot

I used dban http://www.dban.org/ to erase my hd

i used 2 different methods but it doesn't matter, anyway i will tell you that :

in the first computer i used , Gutmann method (xD ) , instead in the second computer : Prng stream 8 pass

Then i have installed successfully kubuntu on both machines, both installed with USB STICK WITH mini iso, in the installer i have selected kubuntu-desktop , without apparent errors , after the standard reboot they did not boot, i have checked the HD and the files were properly installed but the computers did not boot.

I have done a grub-install , chrooting ... and i fixed the problem, so i guess this is a bug in the installer

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: debian-installer (not installed)
ProcVersionSignature: Ubuntu 3.8.0-23.34-generic 3.8.11
Uname: Linux 3.8.0-23-generic x86_64
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
Date: Mon Jul 1 13:41:07 2013
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-05-23 (39 days ago)
InstallationMedia: Kubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MachineType: Sony Corporation SVE1512Y1ESI
MarkForUpload: True
MemoryUsage:
 total used free shared buffers cached
 Mem: 8127116 4112812 4014304 0 24380 457196
 -/+ buffers/cache: 3631236 4495880
 Swap: 8299516 28568 8270948
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-23-generic root=UUID=c1209358-eb8c-4575-a1dd-a2621ae0d077 ro quiet splash vt.handoff=7
SourcePackage: debian-installer
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/30/2012
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: R0150D5
dmi.board.asset.tag: N/A
dmi.board.name: VAIO
dmi.board.vendor: Sony Corporation
dmi.board.version: N/A
dmi.chassis.asset.tag: N/A
dmi.chassis.type: 10
dmi.chassis.vendor: Sony Corporation
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnInsydeCorp.:bvrR0150D5:bd08/30/2012:svnSonyCorporation:pnSVE1512Y1ESI:pvrC10FV64S:rvnSonyCorporation:rnVAIO:rvrN/A:cvnSonyCorporation:ct10:cvrN/A:
dmi.product.name: SVE1512Y1ESI
dmi.product.version: C10FV64S
dmi.sys.vendor: Sony Corporation