  We study short--time existence, long--time existence, finite speed of
propagation, and finite--time blow--up of nonnegative solutions for long-wave
unstable thin film equations $h_t = -a_0(h^n h_{xxx})_x - a_1(h^m h_x)_x$ with
$n>0$, $a_0 > 0$, and $a_1 >0$. The existence and finite speed of propagation
results extend those of [Comm Pure Appl Math 51:625--661, 1998]. For $0<n<2$ we
prove the existence of a nonnegative, compactly--supported, strong solution on
the line that blows up in finite time. The construction requires that the
initial data be nonnegative, compactly supported in $\R^1$, be in $H^1(\R^1)$,
and have negative energy. The blow-up is proven for a large range of $(n,m)$
exponents and extends the results of [Indiana Univ Math J 49:1323--1366, 2000].
