alternate and server images fail to install: d-i stops with "Your installation CD-ROM couldn't be mounted"

Binary package hint: debian-installer

ISO Smoke Testing: ubuntu alternate and server amd64/i386 - 20110224
Testing Environment: VBox and qemu

On server and alternate images, installation stops at 'Detect and mount CD-ROM' with the message "Your installation CD-ROM couldn't be mounted".

The last line of syslog are attached as a screenshot.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: debian-installer (not installed)
ProcVersionSignature: Ubuntu 2.6.38-4.31-generic 2.6.38-rc5
Uname: Linux 2.6.38-4-generic i686
Architecture: i386
Date: Thu Feb 24 11:27:28 2011
EcryptfsInUse: Yes
MachineType: ASUSTeK Computer Inc. U3SG
MemoryUsage:
 total used free shared buffers cached
 Mem: 3087272 2191608 895664 0 115696 1242964
 -/+ buffers/cache: 832948 2254324
 Swap: 5855688 148 5855540
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.utf8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-4-generic root=UUID=75f23f17-3ace-4485-af57-a7318eb6c2ff ro quiet splash vt.handoff=7
SourcePackage: ubiquity
dmi.bios.date: 01/28/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 305
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: U3SG
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr305:bd01/28/2008:svnASUSTeKComputerInc.:pnU3SG:pvr1.0:rvnASUSTeKComputerInc.:rnU3SG:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: U3SG
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.