Version:           0.12.3 (using KDE KDE 3.5.5)
Installed from:    Ubuntu Packages
Compiler:          gcc version 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5) 
OS:                Linux

I started Kopete and created an MSN, ICQ and Yahoo account in that order.  When I closed and opened it, it had "forgotten" the MSN account, although the contacts were still there.  The account did not appear in the configuration dialogue at all.

I can re-add the account (although this has the consequence of creating duplicate contacts every time) and all is well, but this account disappears everytime I close Kopete.

Starting from the console gives this output:

Invalid group header at /home/johncc/.kde/share/config/kopeterc:50
Invalid entry (missing '=') at /home/johncc/.kde/share/config/kopeterc:51
Invalid group header at /home/johncc/.kde/share/config/kopeterc:50
Invalid entry (missing '=') at /home/johncc/.kde/share/config/kopeterc:51
Invalid group header at /home/johncc/.kde/share/config/kopeterc:50
Invalid entry (missing '=') at /home/johncc/.kde/share/config/kopeterc:51

I checked the file in question and found this around the lines mentioned:

[Account_YahooProtocol_johncarlyleclarke
]
AccountId=johncarlyleclarke\n
Protocol=YahooProtocol

When I removed the spurious line break, those startup errors went.  I tried re-adding my MSN account.  During that, I got the following output:

libkopete: WARNING: [void Kopete::AccountManager::slotPluginLoaded(Kopete::Plugin*)] Failed to create account for 'johncarlyleclarke
libkopete: '
QTextImage: no mimesource for kopete-contact-icon:MSNProtocol:jpcc%40bigfoot.com:jamesryall%40msn.com
QMetaObject::findSignal:ClientStream: Conflict with Stream::readyRead()
Transfer ACCEPTED by: LoginTask
Transfer ACCEPTED by: LoginTask
Transfer ACCEPTED by: ListTask
Transfer ACCEPTED by: StatusNotifierTask
Transfer ACCEPTED by: MailNotifierTask
QGArray::find: Index 0 out of range
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished
QObject::disconnect: No such signal Client::gotBuddyIconRequest(const QString&)
CLIENT: Task: Task::done()
CLIENT: Task: emitting finished

Looking at the kopeterc file after closing the app, it looks a bit mangled (extract):

[Account_YahooProtocol_johncarlyleclarke]
AccountId=johncarlyleclarke\n
Protocol=YahooProtocol

[Account_YahooProtocol_johncarlyleclarke
]
AccountId=johncarlyleclarke\n
Priority=1
Protocol=YahooProtocol
YABLastMerge=0
YABLastRemoteRevision=1165318857

On restart the original output ("Invalid group header" etc.) is back, although the MSN account has stayed this time.