Well I looked on the sourcemod forums and searched elsewhere for this issue - but I couldn't find anything on it - if it was a sourcemod bug I would have thought someone else would have noticed it.
It's definitely not a TF2 bug as again, I'm sure it would have been fixed by now.
So I can only think that it's a plugin conflict or something like that, but I can't see anything obvious that would cause a problem. It's not like I have the nextmap or randomcycle plugins enabled.
It also doesn't do it every map change - so I don't know what is different some times over others.
I really need to find a solution as it's pretty much the only thing that causes the server to crash, and it won't automatically restart as it hangs/freezes, rather than closing (which would cause it to restart again automatically).
The plugins on the server are as follows:
[SM] Listing 28 plugins:
01 "Admin File Reader" (1.3.

by AlliedModders LLC
02 "Admin Help" (1.3.

by AlliedModders LLC
03 "Admin Menu" (1.3.

by AlliedModders LLC
04 "Advertisements" (0.5.5) by Tsunami
05 "AFK Manager" (2.6) by Liam
06 "Anti-Flood" (1.3.

by AlliedModders LLC
07 "Basic Ban Commands" (1.3.

by AlliedModders LLC
08 "Basic Chat" (1.3.

by AlliedModders LLC
09 "Basic Comm Control" (1.3.

by AlliedModders LLC
10 "Basic Commands" (1.3.

by AlliedModders LLC
11 "Basic Info Triggers" (1.3.

by AlliedModders LLC
12 "Basic Votes" (1.3.

by AlliedModders LLC
13 "TF2 Class Restrictions" (0.5.1) by Tsunami, Winter Phoenix
14 "Client Preferences" (1.3.

by AlliedModders LLC
15 "TF2 Fast Respawn" (1.2) by Tsunami
16 "Fun Commands" (1.3.

by AlliedModders LLC
17 "Fun Votes" (1.3.

by AlliedModders LLC
18 "gameME Plugin" (3.3) by TTS Oetzel & Goerz GmbH
19 "[TF2] gScramble Team Manager" (2.5.3) by Goerge
20 "High Ping Kicker - Lite Edition" (1.0.0.1) by Liam
21 "MapChooser" (1.3.

by AlliedModders LLC
22 "Map Nominations" (1.3.

by AlliedModders LLC
23 "Player Commands" (1.3.

by AlliedModders LLC
24 "Reserved Slots" (1.3.

by AlliedModders LLC
25 "Rock The Vote" (1.3.

by AlliedModders LLC
26 "Sound Commands" (1.3.

by AlliedModders LLC
27 "Spray Tracer" (5.8a) by Nican132, CptMoore, Lebson506th
28 "TF2 Permanent Critvote" (0.0.4b) by Sillium