Dynamips router gives me a flapping link when using ppp multilink

[Technologov]

IOS image: c7200-adventerprisek9-mz.152-4.S5.bin
GNS3 0.8.6 on Windows 7 x64
Dynamips 0.2.10

Problem:
PPP Multilink on Dynamips gives me a flapping link when connected more than 1 hop away ! (like R3 to R5)

Topology --

When ppp multilink is configured between R4 and R5, remote ping from R3 to R5 is flapping... like this:

R3#ping 219.17.100.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 219.17.100.2, timeout is 2 seconds:
.!!..
Success rate is 40 percent (2/5), round-trip min/avg/max = 64/66/68 ms
R3#ping 219.17.100.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 219.17.100.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R3#ping 219.17.100.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 219.17.100.2, timeout is 2 seconds:
!!!!.

=== PPP Multilink configuration

This is simple -- connect 2x serials (s1/2 and s1/3) on two routers (R4 and R5).

!
interface Multilink1
ip address 219.17.100.1 255.255.255.0
ppp multilink
ppp multilink group 1
!
!
interface Serial1/2
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
serial restart-delay 0
!
interface Serial1/3
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
serial restart-delay 0
!

Workaround:
(config)# no ip cef
This command restores ping !

Strange NOTE:
Neighboring routers connect fine !
R4 can ping to R5, no problem ! Only 1 hop away is a problem !

-Technologov, 23.07.2014.