diff --git a/Makefile b/Makefile
index 2393faa..c7daebb 100644
--- a/Makefile
+++ b/Makefile
@@ -68,7 +68,7 @@ INSTALL_SBIN  = extlinux/extlinux
 # Things to install in /usr/lib/syslinux
 INSTALL_AUX   =	core/pxelinux.0 gpxe/gpxelinux.0 core/isolinux.bin \
 		core/isolinux-debug.bin \
-		dos/syslinux.com win32/syslinux.exe \
+		dos/syslinux.com \
 		mbr/*.bin $(MODULES)
 INSTALL_AUX_OPT = win32/syslinux.exe
 
diff --git a/core/Makefile b/core/Makefile
index 65418c4..fbb38b5 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -66,6 +66,7 @@ kwdhash.gen: keywords genhash.pl
 iso%.bin: iso%.elf checksumiso.pl
 	$(OBJCOPY) -O binary $< $@
 	$(PERL) checksumiso.pl $@
+	-./add_crc $@
 
 # Standard rule for {ldlinux,pxelinux,extlinux}.bin
 %.bin: %.elf
diff --git a/core/add_crc b/core/add_crc
new file mode 100644
index 0000000..0da2307
--- /dev/null
+++ b/core/add_crc
@@ -0,0 +1,57 @@
+#! /usr/bin/perl
+
+use integer;
+
+# for isolinux
+#
+# Ensure checksum over (first sector - 64 bytes) [internally: FirstSecSum]
+# is 0 by adjusting the variable csum_value.
+#
+# Though isolinux checks the integrity with a separate checksum after all
+# data has been loaded this does not help with BIOSes that don't get even
+# the first 2k right. Hence this additional check. :-(
+#
+
+$file = shift;
+$list = "$file";
+$list =~ s/\.bin$/.lsr/;
+
+open F, $list;
+
+while(<F>) {
+  if(/^\s*\d+\s*(\S+)\s*0+\s*(\<\d+\>\s*)?csum_value\s*dd\s*0/) {
+    $ofs = hex $1;
+  }
+}
+close F;
+
+die "oops 1\n" unless $ofs && !($ofs & 3);
+
+# print "$ofs\n";
+
+open F, $file or die "$file: $!\n";
+
+$file_size = -s $file;
+
+sysread F, $buf, $file_size;
+
+close F;
+
+die "oops 1\n" if $file_size != length($buf);
+
+@x = unpack "V512", $buf;
+
+for ($sum = 0, $i = 16; $i < 512; $i++) {
+  $sum += $x[$i];
+}
+
+# printf "0x%08x\n", $sum;
+
+$ns = pack "V", -$sum;
+
+substr($buf, $ofs, 4) = $ns;
+
+open F, ">$file" or die "$file: $!\n";
+
+syswrite F, $buf;
+
diff --git a/core/isolinux.asm b/core/isolinux.asm
index 54f2e19..72be12a 100644
--- a/core/isolinux.asm
+++ b/core/isolinux.asm
@@ -308,6 +308,22 @@ initial_csum:	xor edi,edi
 		mov [FirstSecSum],edi
 
 		mov [DriveNumber],dl
+
+		; check whether the BIOS did load us correctly
+		cmp dl,80h			; some BIOSes try to do floppy emulation...
+		jb bios_err
+		cmp dword [FirstSecSum], byte 0
+		jmp bios_ok	; ##############
+		jz bios_ok
+bios_err:
+		mov si,broken_bios_msg
+		call writemsg
+		jmp short $
+broken_bios_msg	db 13, 10, 'Cannot boot from this CD. Please try a BIOS update.', 13, 10, 0
+		align 4
+csum_value	dd 0
+bios_ok:
+
 %ifdef DEBUG_MESSAGES
 		mov si,startup_msg
 		call writemsg
@@ -336,6 +352,9 @@ initial_csum:	xor edi,edi
 		cmp word [BIOSType],bios_cdrom
 		jne found_drive			; If so, no spec packet...
 
+%if 0
+		; Some BIOSes don't like that call.
+
 		; Now figure out what we're actually doing
 		; Note: use passed-in DL value rather than 7Fh because
 		; at least some BIOSes will get the wrong value otherwise
@@ -356,6 +375,8 @@ initial_csum:	xor edi,edi
 		call crlf
 %endif
 
+%endif
+
 found_drive:
 		; Alright, we have found the drive.  Now, try to find the
 		; boot file itself.  If we have a boot info table, life is
@@ -480,6 +501,9 @@ integrity_ok:
 %endif
 		jmp all_read			; Jump to main code
 
+%if 0
+		; doesn't work anyway, see above
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Start of BrokenAwardHack --- 10-nov-2002           Knut_Petersen@t-online.de
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -671,6 +695,7 @@ spec_query_failed:
 		mov si,trysbm_msg
 		call writemsg
 		jmp .found_drive		; Pray that this works...
+%endif
 
 fatal_error:
 		mov si,nothing_msg
@@ -936,8 +961,18 @@ maxtrans:
 getlinsec_cdrom:
 		mov si,dapa			; Load up the DAPA
 		mov [si+4],bx
-		mov [si+6],es
 		mov [si+8],eax
+
+		; seems that some BIOSes have problems if the target
+		; segment is 0 (don't ask); to avoid this, we normalize
+		; the buffer address here
+		; -> seen on Acer TravelMate C102Ti
+		and word [si+4],0fh
+		mov ax,es
+		shr bx,4
+		add ax,bx
+		mov [si+6],ax
+
 .loop:
 		push bp				; Sectors left
 		cmp bp,[MaxTransferCD]
@@ -1770,6 +1805,7 @@ default_str	db 'default', 0
 default_len	equ ($-default_str)
 boot_dir	db '/boot'			; /boot/isolinux
 isolinux_dir	db '/isolinux', 0
+zb 64
 config_name	db 'isolinux.cfg', 0
 err_disk_image	db 'Cannot load disk image (invalid file)?', CR, LF, 0